Special carbon-based microbial organic-inorganic compound fertilizer for sunflowers

Abstract

The invention relates to the technical field of fertilizers, in particular to a special carbon-based microbial organic-inorganic compound fertilizer for sunflowers. The special carbon-based microbial organic-inorganic compound fertilizer for sunflowers is prepared by mixing and granulating microorganism-loaded biomass charcoal, urea, decomposed cow dung and deionized water, the microorganism-loaded biomass charcoal is obtained by carboxylating biomass charcoal, grafting trehalose and loading microorganisms; the prepared special carbon-based microbial organic-inorganic compound fertilizer for sunflowers can obviously reduce the pH value of soil, improve the acid-base balance of the soil and provide a more suitable soil environment for the growth of the sunflowers.

Description

Technical Field

[0001] The invention relates to the technical field of fertilizers, and in particular to a carbon-based microbial organic-inorganic compound fertilizer special for sunflowers. Background Art

[0002] Soil quality is an important foundation for agricultural production, but due to long-term unreasonable fertilization and farming methods, problems such as soil degradation, acid-base imbalance, and low nutrient utilization have become increasingly prominent. In alkaline soils, trace elements such as phosphorus, iron, manganese, and zinc are easily fixed, resulting in the inability of plants to absorb them effectively, which seriously affects the growth and development of crops. Especially under alkaline soil conditions, the decline in nutrient effectiveness will directly limit the growth and yield of crops, making it difficult for farmers to achieve the goal of increasing production and income. As an important economic crop, sunflower has high requirements for the soil environment, especially its strong sensitivity to nutrient absorption. Under alkaline soil conditions, the growth indicators of sunflowers are often significantly restricted, resulting in a decrease in yield and quality. Therefore, the development of a fertilizer that can improve the acid-base balance of the soil, increase nutrient effectiveness, and significantly promote the growth of sunflowers has important agricultural production significance and economic value.

[0003] In recent years, biochar has gradually become a new type of soil conditioner due to its unique porous structure, large specific surface area and rich surface functional groups. Biochar can not only improve the physical structure of the soil, but also improve the nutrient supply capacity of the soil through adsorption and slow release. However, there are some problems when traditional biochar is used in soil, such as poor compatibility with microorganisms and single function after long-term use, which limits its application potential in compound fertilizers. Therefore, how to improve the functionality of biochar through surface modification has become one of the research hotspots. Summary of the invention

[0004] In view of this, the purpose of the present invention is to propose a carbon-based microbial organic-inorganic compound fertilizer specifically for sunflowers, so as to provide a compound fertilizer that can improve alkaline soil and promote the growth of sunflowers.

[0005] Based on the above purpose, the present invention provides a carbon-based microbial organic-inorganic compound fertilizer for sunflowers, which is obtained by mixing and granulating 4-6 parts of biochar loaded with microorganisms, 1.5-2.5 parts of urea, 1-3 parts of decomposed cow dung and 8-12 parts of deionized water in weight ratio.

[0006] Furthermore, the preparation method of the microorganism-loaded biochar is as follows: (1) Mix rice straw, potassium dihydrogen phosphate and deionized water, grind for 20-40 minutes, place in a cool place for 20-30 hours after grinding, calcine, grind and sieve to obtain biochar; (2) adding the biochar to a sulfuric acid aqueous solution, ultrasonicating for 5-15 minutes, then adding ammonium persulfate, heating to 55-65°C, stirring and reacting for 5-7 hours, and after the reaction is completed, washing and drying to obtain carboxylated biochar; (3) Add the carboxylated biochar to dimethyl sulfoxide, perform ultrasonic treatment for 20-40 min, then add trehalose, raise the temperature to 110-130 °C, add N-methylimidazole, stir and react for 5-7 h, wash and dry after the reaction to obtain trehalose-modified biochar; (4) Add polyvinyl alcohol to deionized water, heat to 75-85°C, stir for 20-40 min, then add sodium alginate, stir for 20-40 min, then add trehalose-modified biochar, ultrasonicate for 15-25 min, heat to 120-126°C, sterilize for 20-30 min, cool to room temperature, add bacterial suspension, stir for 20-40 min, then drop calcium chloride solution, cross-link at 0-8°C for 8-15 h, and then wash with physiological saline to obtain biochar loaded with microorganisms.

[0007] Preferably, in step (1), the weight ratio of rice straw, potassium dihydrogen phosphate and deionized water is 10:1.5-2.5:4-6.

[0008] Preferably, the calcination in step (1) is carried out under nitrogen protection at 8-12°C·min -1 The heating rate is from room temperature to 550-650℃, kept at this temperature for 2-4h, and cooled to room temperature.

[0009] Preferably, in step (2), the weight ratio of biochar, aqueous sulfuric acid solution and ammonium persulfate is 4-6:30-80:3-10.

[0010] Preferably, the concentration of the aqueous sulfuric acid solution is 1.5-2.5 mol·L -1 .

[0011] Preferably, in step (3), the weight ratio of carboxylated biochar, dimethyl sulfoxide, trehalose and N-methylimidazole is 4-6:40-60:0.2-1:0.1-1.5.

[0012] Preferably, in step (4), the ratio of trehalose-modified biochar to bacterial suspension is 4-6 g: 1.5-2.5 mL.

[0013] Preferably, the bacterial suspension in step (4) is a suspension of Bacillus amyloliquefaciens with a concentration of 1×10 9 -1×10 10 CFU / mL.

[0014] Preferably, the strain number of the Bacillus amyloliquefaciens is CGMCC1.0460.

[0015] Preferably, the preparation method of the bacterial suspension in step (4) is as follows: inoculate Bacillus amyloliquefaciens in TSB liquid culture medium, culture in a shaker at 28°C and 180 rpm until the logarithmic growth phase, collect the bacteria by centrifugation at 8000 rpm, and prepare the bacteria into a bacterial suspension with physiological saline.

[0016] Preferably, in step (4), the weight ratio of polyvinyl alcohol, deionized water, sodium alginate, trehalose-modified biochar and calcium chloride solution is 0.5-1.5:40-60:3-8:4-6:30-100.

[0017] Preferably, the concentration of the calcium chloride solution in step (4) is 4wt%-6wt%.

[0018] Preferably, the preparation method of the carbon-based microbial organic-inorganic compound fertilizer for sunflower is as follows: add urea to deionized water, stir for 20-40 minutes, then add biochar loaded with microorganisms and decomposed cow dung, continue stirring for 15-25 minutes, then dry at 60-68°C for 5-7 hours, finally granulate, and air-dry to obtain the carbon-based microbial organic-inorganic compound fertilizer for sunflower.

[0019] Beneficial effects of the present invention: The carbon-based microbial organic-inorganic compound fertilizer specially prepared for sunflowers can significantly reduce the pH value of the soil, improve the acid-base balance of the soil, and increase the effectiveness of trace elements such as phosphorus, iron, manganese, and zinc that are easily fixed under high pH conditions, thereby providing a more suitable soil environment for the growth of sunflowers.

[0020] The carbon-based microbial organic-inorganic compound fertilizer for sunflowers of the present invention modifies biochar. On the one hand, the carboxylated biomass optimizes the acid-base balance of the soil, and also provides uniform sites for the subsequent attachment of trehalose, thereby improving the fixation efficiency of Bacillus amyloliquefaciens. On the other hand, the trehalose-modified biochar has better compatibility and adhesion with Bacillus amyloliquefaciens, thereby improving the activity and long-term colonization ability of Bacillus amyloliquefaciens, further promoting the release and conversion of soil nutrients, and improving the effectiveness of soil nutrients.

[0021] The carbon-based microbial organic-inorganic compound fertilizer for sunflowers of the present invention improves soil structure, increases water retention and air permeability, enhances soil microbial diversity and fertility, and significantly improves growth indicators of sunflowers such as plant height, aboveground dry matter mass and leaf area. DETAILED DESCRIPTION

[0022] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0023] In the specific implementation manner of the present invention, the strain number of Bacillus amyloliquefaciens is CGMCC1.0460, which was purchased from Shanghai Preservation Biotechnology Center, and the decomposed cow dung was purchased from Baoding Wobang Organic Fertilizer Production Co., Ltd., with an effective ingredient content of 45%.

[0024] Example 1: (1) 10 g of rice straw, 1.5 g of potassium dihydrogen phosphate and 4 g of deionized water were mixed and ground for 20 min. After grinding, the mixture was placed in a cool place for 20 h. The mixture was then placed in a muffle furnace and heated at 8 °C min under nitrogen protection. -1 The heating rate was increased from room temperature to 550°C, kept at this temperature for 2 h, cooled to room temperature, and ground through a 0.15 mm sieve to obtain biochar; (2) Add 4 g of biochar to 30 g of 1.5 mol·L -1 The mixture was placed in a sulfuric acid aqueous solution, ultrasonicated for 5 minutes, and then 3 g of ammonium persulfate was added. The temperature was raised to 55°C and stirred for 5 hours. After the reaction was completed, the mixture was washed with deionized water and ethanol for 3 times respectively, and dried at 80°C for 12 hours to obtain carboxylated biochar. (3) Add 4 g of carboxylated biochar to 40 g of dimethyl sulfoxide, ultrasonicate for 20 min, add 0.2 g of trehalose, heat to 110 °C, add 0.1 g of N-methylimidazole, stir and react for 5 h. After the reaction, wash with ethanol three times and dry at 80 °C for 12 h to obtain trehalose-modified biochar. (4) Inoculate Bacillus amyloliquefaciens in TSB liquid medium, culture in a shaker at 28°C and 180 rpm until the logarithmic growth phase, collect the cells by centrifugation at 8000 rpm, and make 1×10 10 CFU / mL of bacterial suspension; (5) Add 0.5 g of polyvinyl alcohol-2488 to 40 g of deionized water, heat to 75 ° C, stir for 20 min, add 3 g of sodium alginate, stir for 20 min, add 4 g of trehalose-modified biochar, ultrasonicate for 15 min, heat to 125 ° C, sterilize for 24 min, cool to room temperature, add 1.5 mL of bacterial suspension, stir for 20 min, and then use a sterile syringe to drop 30 g of 4 wt% calcium chloride solution, cross-link at 0 ° C for 8 h, and then wash 3 times with saline to obtain biochar loaded with microorganisms; (6) Add 1.5 g of urea to 8 g of deionized water and stir for 20 min. Then add 4 g of biochar loaded with microorganisms and 1 g of decomposed cow dung and continue stirring for 15 min. Then dry at 60 °C for 5 h. Finally, put it into a granulator for granulation and air-dry to obtain a carbon-based microbial organic-inorganic compound fertilizer for sunflowers.

[0025] Example 2: (1) 10 g of rice straw, 2 g of potassium dihydrogen phosphate and 5 g of deionized water were mixed and ground for 30 min. After grinding, the mixture was placed in a cool place for 24 h. The mixture was then placed in a muffle furnace and heated at 10 °C min under nitrogen protection. -1 The heating rate was increased from room temperature to 600°C, kept at this temperature for 3 h, cooled to room temperature, and ground through a 0.15 mm sieve to obtain biochar; (2) Add 5 g of biochar to 50 g of 2 mol·L -1 The mixture was placed in a sulfuric acid aqueous solution, ultrasonicated for 10 min, and then 5 g of ammonium persulfate was added. The temperature was raised to 60 ° C, and stirred for 6 h. After the reaction, it was washed with deionized water and ethanol for 3 times respectively, and dried at 80 ° C for 12 h to obtain carboxylated biochar. (3) Add 5 g of carboxylated biochar to 50 g of dimethyl sulfoxide, ultrasonicate for 30 min, add 0.5 g of trehalose, heat to 120 °C, add 0.5 g of N-methylimidazole, stir and react for 6 h. After the reaction, wash with ethanol three times and dry at 80 °C for 12 h to obtain trehalose-modified biochar. (4) Inoculate Bacillus amyloliquefaciens in TSB liquid medium, culture in a shaker at 28°C and 180 rpm until the logarithmic growth phase, collect the cells by centrifugation at 8000 rpm, and make 1×10 10 CFU / mL of bacterial suspension; (5) Add 1g of polyvinyl alcohol-2488 to 50g of deionized water, heat to 80°C, stir for 30min, add 5g of sodium alginate, stir for 30min, add 5g of trehalose-modified biochar, ultrasonicate for 20min, heat to 125°C, sterilize for 24min, cool to room temperature, add 2mL of bacterial suspension, stir for 30min, then use a sterile syringe to drop 50g of 5wt% calcium chloride solution, cross-link at 4°C for 12h, and wash three times with saline to obtain biochar loaded with microorganisms; (6) Add 2 g of urea to 10 g of deionized water and stir for 30 min. Then add 5 g of biochar loaded with microorganisms and 2 g of decomposed cow dung and continue stirring for 20 min. Then dry at 65 °C for 6 h. Finally, put it into a granulator for granulation and air-dry to obtain a carbon-based microbial organic-inorganic compound fertilizer for sunflowers.

[0026] Example 3: (1) 10 g of rice straw, 2.5 g of potassium dihydrogen phosphate and 6 g of deionized water were mixed and ground for 40 min. After grinding, the mixture was placed in a cool place for 30 h. The mixture was then placed in a muffle furnace and heated at 12 °C min under nitrogen protection. -1 The heating rate was increased from room temperature to 650°C, kept at this temperature for 4 h, cooled to room temperature, and ground through a 0.15 mm sieve to obtain biochar; (2) Add 6 g of biochar to 80 g of 2.5 mol·L -1 The mixture was placed in a sulfuric acid aqueous solution, ultrasonicated for 15 min, and then 10 g of ammonium persulfate was added. The temperature was raised to 65 ° C and stirred for 7 h. After the reaction was completed, it was washed with deionized water and ethanol for 3 times respectively, and dried at 80 ° C for 12 h to obtain carboxylated biochar. (3) Add 6 g of carboxylated biochar to 60 g of dimethyl sulfoxide, ultrasonicate for 40 min, add 1 g of trehalose, heat to 130 °C, add 1.5 g of N-methylimidazole, stir and react for 7 h. After the reaction, wash with ethanol three times and dry at 80 °C for 12 h to obtain trehalose-modified biochar. (4) Inoculate Bacillus amyloliquefaciens in TSB liquid medium, culture in a shaker at 28°C and 180 rpm until the logarithmic growth phase, collect the cells by centrifugation at 8000 rpm, and make 1×10 10 CFU / mL of bacterial suspension; (5) Add 1.5 g of polyvinyl alcohol-2488 to 60 g of deionized water, heat to 85 ° C, stir for 40 min, add 8 g of sodium alginate, stir for 40 min, add 6 g of trehalose-modified biochar, ultrasonicate for 25 min, heat to 125 ° C, sterilize for 24 min, cool to room temperature, add 2.5 mL of bacterial suspension, stir for 40 min, and then use a sterile syringe to drop 100 g of 4 wt% calcium chloride solution, cross-link at 8 ° C for 15 h, and then wash three times with saline to obtain biochar loaded with microorganisms; (6) Add 2.5 g of urea to 12 g of deionized water and stir for 40 min. Then add 6 g of biochar loaded with microorganisms and 3 g of decomposed cow dung and continue stirring for 25 min. Then dry at 68 °C for 7 h. Finally, put it into a granulator for granulation and air-dry to obtain a carbon-based microbial organic-inorganic compound fertilizer for sunflowers.

[0027] Comparative Example 1: The difference between Comparative Example 1 and Example 2 is that the trehalose-modified biochar in step (5) is replaced with carboxylated biochar. The specific steps are as follows: (1) Mix 10 g of rice straw, 2 g of potassium dihydrogen phosphate and 5 g of deionized water, grind for 30 min, place in a cool place for 24 h, and then place in a muffle furnace under nitrogen protection at 10 °C min -1 The heating rate was increased from room temperature to 600°C, kept at this temperature for 3 h, cooled to room temperature, and ground through a 0.15 mm sieve to obtain biochar; (2) Add 5 g of biochar to 50 g of 2 mol·L -1The mixture was placed in a sulfuric acid aqueous solution, ultrasonicated for 10 min, and then 5 g of ammonium persulfate was added. The temperature was raised to 60 ° C, and stirred for 6 h. After the reaction, it was washed with deionized water and ethanol for 3 times respectively, and dried at 80 ° C for 12 h to obtain carboxylated biochar. (3) Inoculate Bacillus amyloliquefaciens in TSB liquid medium, culture in a shaker at 28°C and 180 rpm until the logarithmic growth phase, collect the cells by centrifugation at 8000 rpm, and make 1×10 10 CFU / mL of bacterial suspension; (4) Add 1g of polyvinyl alcohol-2488 to 50g of deionized water, heat to 80°C, stir for 30min, add 5g of sodium alginate, stir for 30min, add 5g of carboxylated biochar, ultrasonicate for 20min, heat to 125°C, sterilize for 24min, cool to room temperature, add 2mL of bacterial suspension, stir for 30min, then use a sterile syringe to drop 50g of 5wt% calcium chloride solution, cross-link at 4°C for 12h, and then wash 3 times with saline to obtain biochar loaded with microorganisms; (5) Add 2 g of urea to 10 g of deionized water and stir for 30 min. Then add 5 g of biochar loaded with microorganisms and 2 g of decomposed cow dung and continue stirring for 20 min. Then dry at 65 °C for 6 h. Finally, put it into a granulator for granulation and air-dry to obtain compound fertilizer.

[0028] Comparative Example 2: The difference between Comparative Example 2 and Example 2 is that the carboxylated biochar in step (3) is replaced with biochar. The specific steps are as follows: (1) Mix 10 g of rice straw, 2 g of potassium dihydrogen phosphate and 5 g of deionized water, grind for 30 min, place in a cool place for 24 h, and then place in a muffle furnace under nitrogen protection at 10 °C min -1 The heating rate was increased from room temperature to 600°C, kept at this temperature for 3 h, cooled to room temperature, and ground through a 0.15 mm sieve to obtain biochar; (2) Add 5 g of biochar to 50 g of dimethyl sulfoxide, ultrasonicate for 30 min, add 0.5 g of trehalose, heat to 120 °C, add 0.5 g of N-methylimidazole, stir and react for 6 h. After the reaction, wash with ethanol 3 times and dry at 80 °C for 12 h to obtain trehalose-modified biochar; (3) Inoculate Bacillus amyloliquefaciens in TSB liquid medium, culture in a shaker at 28°C and 180 rpm until the logarithmic growth phase, collect the cells by centrifugation at 8000 rpm, and make 1×10 10 CFU / mL of bacterial suspension; (4) Add 1g of polyvinyl alcohol-2488 to 50g of deionized water, heat to 80°C, stir for 30min, add 5g of sodium alginate, stir for 30min, add 5g of trehalose-modified biochar, ultrasonicate for 20min, heat to 125°C, sterilize for 24min, cool to room temperature, add 2mL of bacterial suspension, stir for 30min, then use a sterile syringe to drop 50g of 5wt% calcium chloride solution, cross-link at 4°C for 12h, and wash three times with saline to obtain biochar loaded with microorganisms; (5) Add 2 g of urea to 10 g of deionized water and stir for 30 min. Then add 5 g of biochar loaded with microorganisms and 2 g of decomposed cow dung and continue stirring for 20 min. Then dry at 65 °C for 6 h. Finally, put it into a granulator for granulation and air-dry to obtain compound fertilizer.

[0029] Comparative Example 3: The difference between Comparative Example 3 and Example 2 is that the trehalose-modified biochar in step (5) is replaced with biochar. The specific steps are as follows: (1) Mix 10 g of rice straw, 2 g of potassium dihydrogen phosphate and 5 g of deionized water, grind for 30 min, place in a cool place for 24 h, and then place in a muffle furnace under nitrogen protection at 10 °C min -1 The heating rate was increased from room temperature to 600°C, kept at this temperature for 3 h, cooled to room temperature, and ground through a 0.15 mm sieve to obtain biochar; (2) Inoculate Bacillus amyloliquefaciens in TSB liquid medium, culture in a shaker at 28°C and 180 rpm until the logarithmic growth phase, collect the cells by centrifugation at 8000 rpm, and make 1×10 10 CFU / mL of bacterial suspension; (3) Add 1g of polyvinyl alcohol-2488 to 50g of deionized water, heat to 80°C, stir for 30min, add 5g of sodium alginate, stir for 30min, add 5g of biochar, ultrasonicate for 20min, heat to 125°C, sterilize for 24min, cool to room temperature, add 2mL of bacterial suspension, stir for 30min, then use a sterile syringe to drop 50g of 5wt% calcium chloride solution, cross-link at 4°C for 12h, and then wash 3 times with saline to obtain biochar loaded with microorganisms; (4) Add 2 g of urea to 10 g of deionized water and stir for 30 min. Then add 5 g of biochar loaded with microorganisms and 2 g of decomposed cow dung and continue stirring for 20 min. Then dry at 65 °C for 6 h. Finally, put it into a granulator for granulation and air-dry to obtain compound fertilizer.

[0030] Comparative Example 4: The difference between Comparative Example 4 and Example 2 is that no decomposed cow dung is added in step (6). The specific steps are as follows: (1) Mix 10 g of rice straw, 2 g of potassium dihydrogen phosphate and 5 g of deionized water, grind for 30 min, place in a cool place for 24 h, and then place in a muffle furnace under nitrogen protection at 10 °C min -1 The heating rate was increased from room temperature to 600°C, kept at this temperature for 3 h, cooled to room temperature, and ground through a 0.15 mm sieve to obtain biochar; (2) Add 5 g of biochar to 50 g of 2 mol·L -1 The mixture was placed in a sulfuric acid aqueous solution, ultrasonicated for 10 min, and then 5 g of ammonium persulfate was added. The temperature was raised to 60 ° C, and stirred for 6 h. After the reaction, it was washed with deionized water and ethanol for 3 times respectively, and dried at 80 ° C for 12 h to obtain carboxylated biochar. (3) Add 5 g of carboxylated biochar to 50 g of dimethyl sulfoxide, ultrasonicate for 30 min, add 0.5 g of trehalose, heat to 120 °C, add 0.5 g of N-methylimidazole, stir and react for 6 h. After the reaction, wash with ethanol three times and dry at 80 °C for 12 h to obtain trehalose-modified biochar. (4) Inoculate Bacillus amyloliquefaciens in TSB liquid medium, culture in a shaker at 28°C and 180 rpm until the logarithmic growth phase, collect the cells by centrifugation at 8000 rpm, and make 1×10 10 CFU / mL of bacterial suspension; (5) Add 1g of polyvinyl alcohol-2488 to 50g of deionized water, heat to 80°C, stir for 30min, add 5g of sodium alginate, stir for 30min, add 5g of trehalose-modified biochar, ultrasonicate for 20min, heat to 125°C, sterilize for 24min, cool to room temperature, add 2mL of bacterial suspension, stir for 30min, then use a sterile syringe to drop 50g of 5wt% calcium chloride solution, cross-link at 4°C for 12h, and wash three times with saline to obtain biochar loaded with microorganisms; (6) Add 2 g of urea to 10 g of deionized water and stir for 30 min. Then add 5 g of biochar loaded with microorganisms and continue stirring for 20 min. Then dry at 65 °C for 6 h. Finally, put it into a granulator for granulation and air-dry to obtain a compound fertilizer.

[0031] Performance Test: Test soil: Soil was taken from a sunflower farm in Inner Mongolia, with a sampling depth of 0-40 cm and a silt loam texture. The average soil salt content was 6.4 g·kg-1, pH 8.7, and total nitrogen 0.51 g·kg -1 , total phosphorus 0.56g·kg -1 , Total potassium 16.30g·kg -1 , alkaline nitrogen 33.29 mg kg -1, Available phosphorus 4.63 mg kg -1 , fast-acting potassium 102.71 mg kg -1 、Organic matter 7.12g·kg -1 The sunflower variety used in this experiment was TF9041.

[0032] Experimental design: The experiment was conducted in a greenhouse. The temperature of the greenhouse was 25-28°C during the experiment. The plastic pots used in the experiment were open on the top and sealed on the bottom. The pots were 12 cm high and 14 cm in diameter. Each pot contained 1.5 kg of test soil. 1 g of the compound fertilizer prepared in the embodiment and the comparative example was mixed with 1.5 kg of test soil and then potted. Then, 500 mL of water was evenly irrigated to wash away the salt. The control (CK) was not applied with compound fertilizer. During the experiment, the plants were watered once every 4 days after the first pair of true leaves came out. The amount of water each time was 200 mL, and a total of 18 irrigations were made. The test materials were sown on November 1, and 4 holes were sown in each pot, with 1 seed in each hole and a hole distance of 6 cm. The seeds were repeated 3 times. The seedlings were fixed after the second pair of true leaves came out, and 3 seedlings were left in each pot. The experiment was cultured for 72 days until the sunflower bud stage ended.

[0033] Soil pH determination: After the experiment, soil was taken from between two sunflower plants, brought back to the laboratory for natural air drying, ground, and passed through a 2 mm sieve. The supernatant of the soil solution was extracted at a soil-water ratio of 1:5, and the soil pH was measured using a pH meter. The results are shown in Table 1.

[0034] Determination of agronomic traits of sunflower: At the end of the experiment, the plant height of the sunflower in each pot was measured and the average value was taken. The aboveground part of the plant was withered in a constant temperature box at 105°C for 30 min, and then the temperature was lowered to 80°C and dried to constant weight. The dry mass of the aboveground part was calculated, and the length and width of each leaf were measured respectively to calculate the leaf area. The results are shown in Table 1.

[0035] Table 1 Soil pH and agronomic characteristics of sunflower sample Soil pH Plant height / cm Aboveground dry matter weight / g <![CDATA[Leaf area / cm 2 > Example 1 7.8±0.1 47.01±0.92 1.12±0.04 16.89±0.07 Example 2 7.4±0.1 49.15±1.12 1.35±0.05 17.52±0.06 Example 3 7.2±0.3 48.05±1.35 1.24±0.08 17.75±0.07 Comparative Example 1 7.6±0.1 35.15±0.85 0.95±0.06 16.32±0.04 Comparative Example 2 8.1±0.2 39.24±0.92 1.08±0.07 16.75±0.06 Comparative Example 3 8.3±0.3 33.16±0.32 0.81±0.04 16.11±0.05 Comparative Example 4 8.4±0.2 40.27±1.02 1.21±0.05 17.08±0.06 CK 8.5±0.2 28.42±0.48 0.72±0.03 15.85±0.04 Note: The values ​​in the table are mean ± standard error.

[0036] Data Analysis: From the data of Examples 1-3 and the control group in Table 1, it can be seen that the soil treated with the carbon-based microbial organic-inorganic compound fertilizer for sunflower prepared by the present invention has a significantly lower pH value than the control treatment by 1 unit, indicating that the carbon-based microbial organic-inorganic compound fertilizer can significantly reduce soil alkalinity, which helps to improve the acid-base balance of the soil and increase the effectiveness of nutrients in the soil, especially trace elements such as phosphorus, iron, manganese, and zinc that are easily fixed under high pH conditions. In addition, the plant height, aboveground dry matter mass, and leaf area of ​​sunflowers treated with the carbon-based microbial organic-inorganic compound fertilizer for sunflower prepared by the present invention are higher than those of the control group, indicating that the compound fertilizer can significantly improve the physical and chemical properties and nutrient supply of the soil and promote the growth and development of sunflowers. It may provide a more balanced nutrient release, enhance the water and fertilizer retention capacity of the soil, and improve the root absorption environment, thereby improving the nutrient absorption efficiency of the plant. At the same time, the role of microorganisms in the compound fertilizer may optimize the soil microbial community, promote the activity of beneficial microorganisms, and further improve the utilization rate of nutrients and the growth vitality of plants. These combined effects make sunflower show significant improvements over the control group in growth indicators such as plant height, aboveground dry matter mass and leaf area.

[0037] From the data of Example 2 and Comparative Example 1 in Table 1, it can be seen that the trehalose modification on the surface of biochar can effectively improve the growth indicators of sunflower, such as plant height, aboveground dry matter mass and leaf area. This may be because the trehalose-modified biochar has better compatibility and adhesion with Bacillus amyloliquefaciens, which helps to improve the activity of Bacillus amyloliquefaciens, and the monosaccharides produced by the decomposition of trehalose help to maintain the long-term activity of Bacillus amyloliquefaciens, thereby enhancing its colonization ability and metabolic function in the soil. After the activity of Bacillus amyloliquefaciens is improved, it can promote the release and conversion of nutrients by secreting a variety of enzymes and plant growth-promoting substances (such as indoleacetic acid, cytokinin, etc.), thereby improving the effectiveness of soil nutrients. At the same time, trehalose-modified biochar may also improve the physical and chemical properties of the soil, such as increasing the water retention and air permeability of the soil, optimizing the root growth environment, and further promoting the growth and development of sunflowers. These combined effects significantly improve the growth indicators of sunflower, such as plant height, aboveground dry matter mass and leaf area.

[0038] It can be seen from the data of Example 2 and Comparative Example 2 in Table 1 that carboxylation of the biochar surface can reduce soil pH and improve growth indicators such as sunflower plant height, aboveground dry matter mass and leaf area. This is mainly because the carboxyl groups on the surface of the biochar can improve the acid-base balance of the soil. At the same time, the carboxylated biochar provides attachment sites for trehalose, allowing trehalose to be evenly attached to the surface of the biochar. In addition, the carboxylated biochar can be cross-linked with sodium alginate under the action of calcium ions, thereby improving the fixation efficiency of Bacillus amyloliquefaciens.

[0039] From the data of Example 2 and Comparative Example 3 in Table 1, it can be seen that the compound fertilizer prepared using unmodified biochar as a carrier has limited ability to regulate soil pH, and has poor effects on improving growth indicators such as sunflower plant height, aboveground dry matter mass and leaf area. This is mainly due to the lack of synergistic effects of carboxyl groups and trehalose on the surface of biochar.

[0040] From the data of Example 2 and Comparative Example 4 in Table 1, it can be seen that the post-wrapping of biochar with decomposed cow dung can significantly improve the growth indicators of sunflower such as plant height, aboveground dry matter mass and leaf area. This is mainly because the decomposed cow dung contains a large amount of organic matter resources, which on the one hand improves the activity of Bacillus amyloliquefaciens in the biochar, and on the other hand provides a large amount of organic matter for the soil, which helps to improve soil structure and fertility and increase the diversity of soil microorganisms.

[0041] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

Claims

1. A carbon-based microbial organic-inorganic compound fertilizer for sunflower, characterized in that: According to the weight ratio, 4-6 parts of biomass charcoal loaded with microorganisms, 1.5-2.5 parts of urea, 1-3 parts of decomposed cow dung and 8-12 parts of deionized water are mixed and granulated to obtain; The preparation method of the microorganism-loaded biochar is as follows: (1) Mix rice straw, potassium dihydrogen phosphate and deionized water, grind for 20-40 minutes, place in a cool place for 20-30 hours after grinding, calcine, grind and sieve to obtain biochar; (2) adding the biochar to a sulfuric acid aqueous solution, ultrasonicating for 5-15 minutes, then adding ammonium persulfate, heating to 55-65°C, stirring and reacting for 5-7 hours, and after the reaction is completed, washing and drying to obtain carboxylated biochar; (3) Add the carboxylated biochar to dimethyl sulfoxide, perform ultrasonic treatment for 20-40 min, then add trehalose, raise the temperature to 110-130 °C, add N-methylimidazole, stir and react for 5-7 h, wash and dry after the reaction to obtain trehalose-modified biochar; (4) Add polyvinyl alcohol to deionized water, heat to 75-85°C, stir for 20-40 minutes, then add sodium alginate, stir for 20-40 minutes, then add trehalose-modified biochar, ultrasonicate for 15-25 minutes, heat to 120-126°C, sterilize for 20-30 minutes, cool to room temperature, add bacterial suspension, stir for 20-40 minutes, then drop calcium chloride solution, cross-link at 0-8°C for 8-15 hours, and then wash with physiological saline to obtain biochar loaded with microorganisms; In the step (3), the weight ratio of carboxylated biochar, dimethyl sulfoxide, trehalose and N-methylimidazole is 4-6:40-60:0.2-1:0.1-1.5; In the step (4), the dosage ratio of trehalose-modified biochar to bacterial suspension is 4-6 g: 1.5-2.5 mL.

2. The carbon-based microbial organic-inorganic compound fertilizer for sunflower according to claim 1, characterized in that: In the step (1), the weight ratio of rice straw, potassium dihydrogen phosphate and deionized water is 10:1.5-2.5:4-6.

3. The carbon-based microbial organic-inorganic compound fertilizer for sunflower according to claim 1, characterized in that: In step (1), the calcination is carried out under nitrogen protection at 8-12°C·min -1 The heating rate is from room temperature to 550-650℃, kept at this temperature for 2-4h, and cooled to room temperature.

4. The carbon-based microbial organic-inorganic compound fertilizer for sunflower according to claim 1, characterized in that: In step (2), the weight ratio of biochar, aqueous sulfuric acid solution and ammonium persulfate is 4-6:30-80:3-10; the concentration of aqueous sulfuric acid solution is 1.5-2.5 mol·L -1 .

5. The carbon-based microbial organic-inorganic compound fertilizer for sunflower according to claim 1, characterized in that: The bacterial suspension in step (4) is a suspension of Bacillus amyloliquefaciens with a concentration of 1×10 9 -1×10 10 CFU / mL.

6. The carbon-based microbial organic-inorganic compound fertilizer for sunflower according to claim 1, characterized in that: The preparation method of the bacterial suspension in step (4) is as follows: inoculate Bacillus amyloliquefaciens in TSB liquid culture medium, culture in a shaker at 28°C and 180 rpm until the logarithmic growth phase, collect the bacteria by centrifugation at 8000 rpm, and prepare the bacteria suspension with physiological saline.

7. The carbon-based microbial organic-inorganic compound fertilizer for sunflower according to claim 1, characterized in that: In the step (4), the weight ratio of polyvinyl alcohol, deionized water, sodium alginate, trehalose-modified biochar and calcium chloride solution is 0.5-1.5:40-60:3-8:4-6:30-100.

8. The carbon-based microbial organic-inorganic compound fertilizer for sunflower according to claim 1, characterized in that: The concentration of the calcium chloride solution in step (4) is 4wt%-6wt%.

9. The carbon-based microbial organic-inorganic compound fertilizer for sunflower according to claim 1, characterized in that: The preparation method of the carbon-based microbial organic-inorganic compound fertilizer for sunflower is as follows: urea is added to deionized water, stirred for 20-40 minutes, biochar loaded with microorganisms and decomposed cow dung are added, stirring is continued for 15-25 minutes, and then dried at 60-68° C. for 5-7 hours, and finally granulated and air-dried to obtain the carbon-based microbial organic-inorganic compound fertilizer for sunflower.