A special carbon-based microbial organic-inorganic compound fertilizer for sunflowers

Abstract

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

Description

Technical Field

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

[0002] Soil quality is an important foundation for agricultural production. However, due to long-term unreasonable fertilization and tillage methods, problems such as soil degradation, acid-base imbalance, and low nutrient utilization rate have become increasingly prominent. In alkaline soils, trace elements such as phosphorus, iron, manganese, and zinc are easily fixed, resulting in plants being unable to effectively absorb them, seriously affecting the growth and development of crops. Especially under alkaline soil conditions, the decline in nutrient availability 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 cash crop, sunflowers have relatively high requirements for the soil environment, especially being more sensitive to nutrient absorption. Under alkaline soil conditions, the growth indicators of sunflowers are often significantly restricted, leading to a decline in yield and quality. Therefore, developing a fertilizer that can improve soil acid-base balance, increase nutrient availability, and significantly promote the growth of sunflowers has important agricultural production significance and economic value.

[0003] In recent years, due to its unique porous structure, large specific surface area, and rich surface functional groups, biochar has gradually become a new type of soil conditioner. Biochar can not only improve the physical structure of the soil but also enhance the soil's nutrient supply capacity through adsorption and slow-release effects. However, when traditional biochar is applied to the soil, there are some problems, such as poor compatibility with microorganisms and single function after long-term use, which limit 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 provide a special carbon-based microbial organic-inorganic compound fertilizer for sunflowers 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 special carbon-based microbial organic-inorganic compound fertilizer for sunflowers, which is obtained by mixing 4 - 6 parts of biochar loaded with microorganisms, 1.5 - 2.5 parts of urea, 1 - 3 parts of well-rotted cow dung, and 8 - 12 parts of deionized water according to the weight ratio and granulating.

[0006] Further, the preparation method of the biochar loaded with microorganisms is as follows:

[0007] (1) Mix rice straw, potassium dihydrogen phosphate, and deionized water, grind for 20 - 40 min, place it in a cool place for 20 - 30 h after grinding, then calcine, grind, and sieve to obtain biochar;

[0008] (2) Add biochar into sulfuric acid aqueous solution, ultrasonicate for 5 - 15 min, then add ammonium persulfate, heat up to 55 - 65 °C, stir and react for 5 - 7 h. After the reaction is completed, wash and dry to obtain carboxylated biochar;

[0009] (3) Add carboxylated biochar into dimethyl sulfoxide, ultrasonicate for 20 - 40 min, then add trehalose, heat up to 110 - 130 °C, then add N - methylimidazole, stir and react for 5 - 7 h. After the reaction is completed, wash and dry to obtain trehalose - modified biochar;

[0010] (4) Add polyvinyl alcohol into deionized water, heat up 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 up to 120 - 126 °C, sterilize for 20 - 30 min, cool down to room temperature, add bacterial suspension, stir for 20 - 40 min, then drop in calcium chloride solution, cross - link at 0 - 8 °C for 8 - 15 h, and then wash with normal saline to obtain biochar loaded with microorganisms.

[0011] Preferably, in step (1), the weight ratio of rice straw, potassium dihydrogen phosphate and deionized water is 10:1.5 - 2.5:4 - 6.

[0012] Preferably, in step (1), the calcination is carried out under nitrogen protection, with a heating rate of 8 - 12 °C·min -1 Heat up from room temperature to 550 - 650 °C at this heating rate, hold for 2 - 4 h, and then cool down to room temperature.

[0013] Preferably, in step (2), the weight ratio of biochar, sulfuric acid aqueous solution and ammonium persulfate is 4 - 6:30 - 80:3 - 10.

[0014] Preferably, the concentration of the sulfuric acid aqueous solution is 1.5 - 2.5 mol·L -1 .

[0015] 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.

[0016] Preferably, in step (4), the dosage ratio of trehalose - modified biochar and bacterial suspension is 4 - 6 g:1.5 - 2.5 mL.

[0017] Preferably, in step (4), the bacterial suspension is a Bacillus amyloliquefaciens bacterial suspension with a concentration of 1×10 9 - 1×10 10 CFU / mL.

[0018] Preferably, the strain number of the Bacillus amyloliquefaciens is CGMCC1.0460.

[0019] Preferably, the method for preparing the bacterial suspension in step (4) is as follows: Inoculate Bacillus amyloliquefaciens into TSB liquid medium, culture it in a shaker at 28 °C and 180 rpm until the logarithmic growth phase, collect the bacterial cells by centrifugation at 8000 rpm, and make the bacterial cells into a bacterial suspension with physiological saline.

[0020] Preferably, the weight ratio of polyvinyl alcohol, deionized water, sodium alginate, trehalose-modified biomass carbon, and calcium chloride solution in step (4) is 0.5 - 1.5:40 - 60:3 - 8:4 - 6:30 - 100.

[0021] Preferably, the concentration of the calcium chloride solution in step (4) is 4wt% - 6wt%.

[0022] Preferably, the method for preparing the special sunflower carbon-based microbial organic-inorganic compound fertilizer is as follows: Add urea to deionized water, stir for 20 - 40 min, then add the biomass carbon loaded with microorganisms and well-rotted cow dung, continue to stir for 15 - 25 min, then dry at 60 - 68 °C for 5 - 7 h, and finally granulate and air-dry to obtain the special sunflower carbon-based microbial organic-inorganic compound fertilizer.

[0023] Advantages of the present invention:

[0024] The special sunflower carbon-based microbial organic-inorganic compound fertilizer prepared by the present invention can significantly reduce the pH value of the soil, improve the acid-base balance of the soil, and increase the availability 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.

[0025] For the special sunflower carbon-based microbial organic-inorganic compound fertilizer of the present invention, by modifying the biomass carbon, 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, improving the immobilization efficiency of Bacillus amyloliquefaciens; on the other hand, the trehalose-modified biomass carbon has better compatibility and adhesion with Bacillus amyloliquefaciens, thereby enhancing the activity and long-term colonization ability of Bacillus amyloliquefaciens, further promoting the release and transformation of soil nutrients, and improving the availability of soil nutrients.

[0026] The special sunflower carbon-based microbial organic-inorganic compound fertilizer of the present invention improves the soil structure, increases water retention and air permeability, enhances soil microbial diversity and fertility, and significantly improves the growth indexes of sunflowers such as plant height, above-ground dry matter weight, and leaf area. Specific embodiments

[0027] To make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below in conjunction with specific embodiments.

[0028] In the specific embodiment of the present invention, the strain number of Bacillus amyloliquefaciens is CGMCC 1.0460, purchased from Shanghai Center for Biotechnology Preservation. The well-rotted cow dung is purchased from Baoding Wobang Organic Fertilizer Production Co., Ltd., and the content of the active ingredient is 45%.

[0029] Example 1: (1) Mix 10 g of rice straw, 1.5 g of potassium dihydrogen phosphate and 4 g of deionized water, grind for 20 min, place it in a cool place for 20 h after grinding, then put it into a muffle furnace, under nitrogen protection, with a heating rate of 8 °C·min -1 The heating rate is used to heat from room temperature to 550 °C, keep warm for 2 h, cool to room temperature, grind and pass through a 0.15 mm sieve to obtain biochar;

[0030] (2) Add 4 g of biochar to 30 g of sulfuric acid aqueous solution with a concentration of 1.5 mol·L -1 Ultrasonic for 5 min, then add 3 g of ammonium persulfate, heat up to 55 °C, stir and react for 5 h. After the reaction, wash with deionized water and ethanol three times respectively, and dry at 80 °C for 12 h to obtain carboxylated biochar;

[0031] (3) Add 4 g of carboxylated biochar to 40 g of dimethyl sulfoxide, ultrasonic for 20 min, then add 0.2 g of trehalose, heat up to 110 °C, then 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;

[0032] (4) Inoculate Bacillus amyloliquefaciens in TSB liquid medium, culture it in a shaker at 28 °C and 180 rpm until the logarithmic growth phase, collect the bacteria by centrifugation at 8000 rpm, and make the bacteria into a bacterial suspension of 1×10 10 CFU / mL with physiological saline;

[0033] (5) Add 0.5 g of polyvinyl alcohol-2488 to 40 g of deionized water, heat up to 75 °C, stir for 20 min, then add 3 g of sodium alginate, stir for 20 min, then add 4 g of trehalose-modified biochar, ultrasonic for 15 min, heat up to 125 °C, sterilize for 24 min, cool to room temperature, add 1.5 mL of bacterial suspension, stir for 20 min, then drop it into 30 g of calcium chloride solution with a concentration of 4 wt% with a sterile syringe, crosslink at 0 °C for 8 h, and then wash with physiological saline three times to obtain biochar loaded with microorganisms;

[0034] (6) Add 1.5 g of urea to 8 g of deionized water, stir for 20 min, then add 4 g of biomass charcoal loaded with microorganisms and 1 g of well-rotted cow dung, continue to stir for 15 min, then dry at 60 °C for 5 h, and finally put it into a granulator for granulation and air-dry to obtain a special carbon-based microbial organic-inorganic compound fertilizer for sunflowers.

[0035] Example 2: (1) Mix 10 g of rice straw, 2 g of potassium dihydrogen phosphate and 5 g of deionized water, grind for 30 min, place it in a cool place for 24 h after grinding, then put it into a muffle furnace, under nitrogen protection, at a heating rate of 10 °C·min -1 Heat from room temperature to 600 °C, hold for 3 h, cool to room temperature, grind through a 0.15 mm sieve to obtain biomass charcoal;

[0036] (2) Add 5 g of biomass charcoal to 50 g of sulfuric acid aqueous solution with a concentration of 2 mol·L -1 Ultrasonic for 10 min, then add 5 g of ammonium persulfate, heat up to 60 °C, stir and react for 6 h. After the reaction, wash with deionized water and ethanol three times respectively, and dry at 80 °C for 12 h to obtain carboxylated biomass charcoal;

[0037] (3) Add 5 g of carboxylated biomass charcoal to 50 g of dimethyl sulfoxide, ultrasonic for 30 min, then add 0.5 g of trehalose, heat up to 120 °C, then 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 biomass charcoal;

[0038] (4) Inoculate Bacillus amyloliquefaciens in TSB liquid medium, culture it in a shaker at 28 °C and 180 rpm until the logarithmic growth phase, collect the bacterial cells by centrifugation at 8000 rpm, and make the bacterial cells into a bacterial suspension of 1×10 10 CFU / mL;

[0039] (5) Add 1 g of polyvinyl alcohol-2488 to 50 g of deionized water, heat up to 80 °C, stir for 30 min, then add 5 g of sodium alginate, stir for 30 min, then add 5 g of trehalose-modified biomass charcoal, ultrasonic for 20 min, heat up to 125 °C, sterilize for 24 min, cool to room temperature, add 2 mL of bacterial suspension, stir for 30 min, then drop it into 50 g of calcium chloride solution with a concentration of 5 wt% with a sterile syringe, crosslink at 4 °C for 12 h, and then wash with physiological saline three times to obtain biomass charcoal loaded with microorganisms;

[0040] (6) Add 2 g of urea to 10 g of deionized water, stir for 30 min, then add 5 g of biomass carbon loaded with microorganisms and 2 g of well-rotted cow dung, continue to stir for 20 min, then dry at 65 °C for 6 h, and finally put it into a granulator for granulation and air-dry to obtain a special carbon-based microbial organic-inorganic compound fertilizer for sunflowers.

[0041] Example 3: (1) Mix 10 g of rice straw, 2.5 g of potassium dihydrogen phosphate and 6 g of deionized water, grind for 40 min, place it in a cool place for 30 h after grinding, then put it into a muffle furnace, under nitrogen protection, at a heating rate of 12 °C·min -1 Heat up from room temperature to 650 °C, hold for 4 h, cool to room temperature, grind through a 0.15 mm sieve to obtain biomass carbon;

[0042] (2) Add 6 g of biomass carbon to 80 g of sulfuric acid aqueous solution with a concentration of 2.5 mol·L -1 , ultrasonicate for 15 min, then add 10 g of ammonium persulfate, heat up to 65 °C, stir and react for 7 h. After the reaction, wash with deionized water and ethanol three times respectively, and dry at 80 °C for 12 h to obtain carboxylated biomass carbon;

[0043] (3) Add 6 g of carboxylated biomass carbon to 60 g of dimethyl sulfoxide, ultrasonicate for 40 min, then add 1 g of trehalose, heat up to 130 °C, then 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 biomass carbon;

[0044] (4) Inoculate Bacillus amyloliquefaciens into TSB liquid medium, culture it in a shaker at 28 °C and 180 rpm until the logarithmic growth phase, collect the bacteria by centrifugation at 8000 rpm, and make the bacteria into a bacterial suspension of 1×10 10 CFU / mL;

[0045] (5) Add 1.5 g of polyvinyl alcohol-2488 to 60 g of deionized water, heat up to 85 °C, stir for 40 min, then add 8 g of sodium alginate, stir for 40 min, then add 6 g of trehalose-modified biomass carbon, ultrasonicate for 25 min, heat up to 125 °C, sterilize for 24 min, cool to room temperature, add 2.5 mL of bacterial suspension, stir for 40 min, then drop it into 100 g of calcium chloride solution with a concentration of 4 wt% with a sterile syringe, crosslink at 8 °C for 15 h, and then wash with physiological saline three times to obtain biomass carbon loaded with microorganisms;

[0046] (6) Add 2.5 g of urea to 12 g of deionized water, stir for 40 min, then add 6 g of biomass carbon loaded with microorganisms and 3 g of well-rotted cow dung, continue to stir for 25 min, then dry at 68 °C for 7 h, and finally put it into a granulator for granulation and air-dry to obtain a special carbon-based microbial organic-inorganic compound fertilizer for sunflowers.

[0047] Comparative Example 1: The difference between Comparative Example 1 and Example 2 is that the trehalose-modified biomass carbon in step (5) is replaced by carboxylated biomass carbon. The specific steps are as follows:

[0048] (1) Mix 10 g of rice straw, 2 g of potassium dihydrogen phosphate and 5 g of deionized water, grind for 30 min, place it in a cool place for 24 h after grinding, then put it into a muffle furnace, under nitrogen protection, at a heating rate of 10 °C·min -1 Heat up from room temperature to 600 °C, keep warm for 3 h, cool to room temperature, grind and pass through a 0.15 mm sieve to obtain biomass carbon;

[0049] (2) Add 5 g of biomass carbon to 50 g of sulfuric acid aqueous solution with a concentration of 2 mol·L -1 , ultrasonicate for 10 min, then add 5 g of ammonium persulfate, heat up to 60 °C, stir and react for 6 h. After the reaction is completed, wash with deionized water and ethanol three times respectively, and dry at 80 °C for 12 h to obtain carboxylated biomass carbon;

[0050] (3) Inoculate Bacillus amyloliquefaciens in TSB liquid medium, culture it in a shaker at 28 °C and 180 rpm until the logarithmic growth phase, collect the bacteria by centrifugation at 8000 rpm, and make the bacteria into a bacterial suspension of 1×10 10 CFU / mL;

[0051] (4) Add 1 g of polyvinyl alcohol-2488 to 50 g of deionized water, heat up to 80 °C, stir for 30 min, then add 5 g of sodium alginate, stir for 30 min, then add 5 g of carboxylated biomass carbon, ultrasonicate for 20 min, heat up to 125 °C, sterilize for 24 min, cool to room temperature, add 2 mL of bacterial suspension, stir for 30 min, then drop it into 50 g of calcium chloride solution with a concentration of 5 wt% with a sterile syringe, crosslink at 4 °C for 12 h, and wash with normal saline three times to obtain biomass carbon loaded with microorganisms;

[0052] (5) Add 2 g of urea to 10 g of deionized water, stir for 30 min, then add 5 g of biomass carbon loaded with microorganisms and 2 g of well-rotted cow dung, continue to stir for 20 min, then dry at 65 °C for 6 h, and finally put it into a granulator for granulation and air-dry to obtain a compound fertilizer.

[0053] 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:

[0054] (1) Mix 10 g of rice straw, 2 g of potassium dihydrogen phosphate, and 5 g of deionized water, grind for 30 min, place it in a cool place for 24 h after grinding, then put it into a muffle furnace, and under nitrogen protection, heat from room temperature to 600 °C at a heating rate of 10 °C·min -1 The heating rate is increased to 600 °C, held for 3 h, cooled to room temperature, ground through a 0.15 mm sieve to obtain biochar;

[0055] (2) Add 5 g of biochar to 50 g of dimethyl sulfoxide, ultrasonicate for 30 min, then add 0.5 g of trehalose, heat to 120 °C, then 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;

[0056] (3) Inoculate Bacillus amyloliquefaciens into TSB liquid medium, culture it in a shaker at 28 °C and 180 rpm until the logarithmic growth phase, centrifuge to collect the cells at 8000 rpm, and make the cells into a cell suspension of 1×10 10 CFU / mL;

[0057] (4) Add 1 g of polyvinyl alcohol-2488 to 50 g of deionized water, heat to 80 °C, stir for 30 min, then add 5 g of sodium alginate, stir for 30 min, then add 5 g of trehalose-modified biochar, ultrasonicate for 20 min, heat to 125 °C, sterilize for 24 min, cool to room temperature, add 2 mL of cell suspension, stir for 30 min, then drop it into 50 g of calcium chloride solution with a concentration of 5 wt% using a sterile syringe, crosslink at 4 °C for 12 h, and then wash with normal saline 3 times to obtain biochar loaded with microorganisms;

[0058] (5) Add 2 g of urea to 10 g of deionized water, stir for 30 min, then add 5 g of biochar loaded with microorganisms and 2 g of well-rotted cow dung, continue to stir for 20 min, then dry at 65 °C for 6 h, and finally put it into a granulator for granulation and air-dry to obtain compound fertilizer.

[0059] 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:

[0060] (1) Mix 10 g of rice straw, 2 g of potassium dihydrogen phosphate, and 5 g of deionized water, grind for 30 min, place it in a cool place for 24 h after grinding, then put it into a muffle furnace, and under nitrogen protection, heat from room temperature to 600 °C at a heating rate of 10 °C·min -1The heating rate was from room temperature to 600 °C, holding for 3 h, cooling to room temperature, grinding through a 0.15 mm sieve to obtain biochar;

[0061] (2)Bacillus amyloliquefaciens was inoculated into TSB liquid medium and cultured in a shaker at 28 °C and 180 rpm until the logarithmic growth phase. The cells were collected by centrifugation at 8000 rpm, and the cells were made into a cell suspension of 1×10 10 CFU / mL with physiological saline;

[0062] (3)1 g of polyvinyl alcohol-2488 was added to 50 g of deionized water, heated to 80 °C, stirred for 30 min, then 5 g of sodium alginate was added, stirred for 30 min, then 5 g of biochar was added, sonicated for 20 min, heated to 125 °C, sterilized for 24 min, cooled to room temperature, 2 mL of cell suspension was added, stirred for 30 min, and then dropped into 50 g of calcium chloride solution with a concentration of 5 wt% using a sterile syringe, crosslinked at 4 °C for 12 h, and then washed 3 times with physiological saline to obtain biochar loaded with microorganisms;

[0063] (4)2 g of urea was added to 10 g of deionized water, stirred for 30 min, then 5 g of biochar loaded with microorganisms and 2 g of well-rotted cow dung were added, continued to stir for 20 min, then dried at 65 °C for 6 h, and finally granulated in a granulator and air-dried to obtain compound fertilizer.

[0064] Comparative Example 4: The difference between Comparative Example 4 and Example 2 was that well-rotted cow dung was not added in step (6). The specific steps were as follows:

[0065] (1)10 g of rice straw, 2 g of potassium dihydrogen phosphate and 5 g of deionized water were mixed, ground for 30 min, placed in a cool place for 24 h after grinding, and then put into a muffle furnace. Under nitrogen protection, at a heating rate of 10 °C·min -1 The heating rate was from room temperature to 600 °C, holding for 3 h, cooling to room temperature, grinding through a 0.15 mm sieve to obtain biochar;

[0066] (2)5 g of biochar was added to 50 g of sulfuric acid aqueous solution with a concentration of 2 mol·L -1 Ultrasonic for 10 min, then 5 g of ammonium persulfate was added, heated to 60 °C, stirred and reacted for 6 h. After the reaction, it was washed 3 times with deionized water and ethanol respectively, and dried at 80 °C for 12 h to obtain carboxylated biochar;

[0067] (3)5 g of carboxylated biochar was added to 50 g of dimethyl sulfoxide, sonicated for 30 min, then 0.5 g of trehalose was added, heated to 120 °C, then 0.5 g of N-methylimidazole was added, stirred and reacted for 6 h. After the reaction, it was washed 3 times with ethanol and dried at 80 °C for 12 h to obtain trehalose-modified biochar;

[0068] (4) Inoculate Bacillus amyloliquefaciens into TSB liquid medium and culture it in a shaker at 28 °C and 180 rpm until the logarithmic growth phase. Centrifuge to collect the bacteria at 8000 rpm, and make the bacteria into a bacterial suspension of 1×10 10 CFU / mL with physiological saline;

[0069] (5) Add 1 g of polyvinyl alcohol - 2488 to 50 g of deionized water, heat up to 80 °C, stir for 30 min, then add 5 g of sodium alginate and stir for 30 min. Then add 5 g of trehalose - modified biomass carbon, ultrasonicate for 20 min, heat up to 125 °C, sterilize for 24 min, cool down to room temperature, add 2 mL of the bacterial suspension, stir for 30 min, and then drop it into 50 g of a 5 wt% calcium chloride solution with a sterile syringe. Crosslink at 4 °C for 12 h, and then wash it 3 times with physiological saline to obtain the biomass carbon loaded with microorganisms;

[0070] (6) Add 2 g of urea to 10 g of deionized water, stir for 30 min, then add 5 g of the biomass carbon loaded with microorganisms, continue to stir for 20 min, then dry it at 65 °C for 6 h, and finally granulate it in a granulator and air - dry it to obtain the compound fertilizer.

[0071] Performance test:

[0072] Test soil: Collected from a sunflower farmland soil in Inner Mongolia, the sampling depth is 0 - 40 cm, and the soil texture is silt loam. The average soil salt content is 6.4 g·kg-1, pH is 8.7, total nitrogen is 0.51 g·kg -1 、total phosphorus is 0.56 g·kg -1 、total potassium is 16.30 g·kg -1 、alkali - hydrolyzable nitrogen is 33.29 mg·kg -1 、available phosphorus is 4.63 mg·kg -1 、rapid - available potassium is 102.71 mg·kg -1 、organic matter is 7.12 g·kg -1 . The sunflower variety for this test is TF9041.

[0073] Experimental design: Conducted in a greenhouse. During the experiment, the greenhouse temperature was 25 - 28 °C. The plastic pots used in the experiment had an open top and a sealed bottom, with a height of 12 cm and a diameter of 14 cm. Each pot was filled with 1.5 kg of the tested soil. 1 g of the compound fertilizers prepared in the examples and comparative examples was respectively mixed evenly with 1.5 kg of the tested soil and then put into the pots. Then, 500 mL of water was evenly irrigated to leach the salts. Taking no application of compound fertilizer as the control (CK), during the experiment, after the emergence of the first pair of true leaves, water was applied equally once every 4 days, with each watering amount being 200 mL, and a total of 18 irrigations were carried out. The experimental materials were sown on November 1st, with 4 holes sown in each pot, 1 seed in each hole, and the hole spacing being 6 cm. There were 3 replicates. Thinning was carried out after the emergence of the second pair of true leaves, and 3 seedlings were left in each pot. The experiment ended when the sunflowers reached the budding stage after 72 days of cultivation.

[0074] Soil pH determination: After the experiment ended, soil was taken in the middle of two sunflower plants, brought back to the laboratory, air-dried naturally, ground, and passed through a 2-mm sieve. The supernatant of the soil solution was extracted with a soil-water ratio of 1:5, and the soil pH was measured with a pH meter. The results are shown in Table 1.

[0075] Determination of sunflower agronomic traits: At the end of the experiment, the plant height of the sunflowers in each pot was measured and averaged. The above-ground part of the plants was blanched in an oven at 105 °C for 30 min, and then the temperature was reduced to 80 °C and dried to a constant weight to calculate the dry matter weight of the above-ground part. The length and width of each leaf were measured respectively to calculate the leaf area. The results are shown in Table 1.

[0076] Table 1 Soil pH and sunflower agronomic traits

[0077] 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

[0078] Note: The values in the table are mean ± standard error.

[0079] Data analysis:

[0080] From the data of Examples 1 - 3 and the control group in Table 1, it can be seen that the pH of the soil treated with the sunflower - specific carbon - based microbial organic - inorganic compound fertilizer prepared by the present invention decreased significantly by 1 unit compared with the control treatment, indicating that the carbon - based microbial organic - inorganic compound fertilizer can significantly reduce soil alkalinity. This helps to improve the soil acid - base balance and increase the availability of nutrients in the soil, especially trace elements such as phosphorus, iron, manganese, and zinc that are easily fixed under high - pH conditions. Moreover, under the treatment of the sunflower - specific carbon - based microbial organic - inorganic compound fertilizer prepared by the present invention, the plant height, above - ground dry matter weight, and leaf area of sunflowers are all higher than those of the control group treatment. This shows that this compound fertilizer can significantly improve the physical and chemical properties of the soil and the nutrient supply status, and promote the growth and development of sunflowers. It may enhance the water - holding and fertilizer - retaining capacity of the soil, improve the root absorption environment, and thus increase the nutrient absorption efficiency of plants by providing a more balanced nutrient release. At the same time, the role of the microorganisms in this compound fertilizer may optimize the soil microbial community, promote the activity of beneficial microorganisms, and further improve the nutrient utilization rate and plant growth vitality. These combined effects result in significant improvements in the growth indicators of sunflowers, such as plant height, above - ground dry matter weight, and leaf area, compared with the control group.

[0081] 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 sunflowers, such as plant height, above - ground dry matter weight, 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. Moreover, the monosaccharides produced by the decomposition of trehalose contribute to maintaining 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 transformation of nutrients by secreting various enzymes and plant - promoting substances (such as indole - 3 - acetic acid, cytokinins, etc.), and improve the availability of soil nutrients. At the same time, the trehalose - modified biochar may also improve the physical and chemical properties of the soil, such as increasing soil water - holding capacity and air permeability, and optimizing the root growth environment, thus further promoting the growth and development of sunflowers. These combined effects result in significant improvements in the growth indicators of sunflowers, such as plant height, above - ground dry matter weight, and leaf area.

[0082] From the data of Example 2 and Comparative Example 2 in Table 1, it can be seen that the carboxylation on the surface of biochar can reduce soil pH and improve the growth indicators of sunflowers, such as plant height, above - ground dry matter weight, and leaf area. This is mainly because the carboxyl groups on the surface of biochar can improve the soil acid - base balance. At the same time, the carboxylated biochar provides an attachment site for trehalose, enabling trehalose to be evenly attached to the surface of biochar. Moreover, the carboxylated biochar can cross - link with sodium alginate under the action of calcium ions to improve the immobilization efficiency of Bacillus amyloliquefaciens.

[0083] As can be seen from the data of Example 2 and Comparative Example 3 in Table 1, the compound fertilizer prepared with unmodified biochar as the carrier has limited ability to adjust soil pH and poor improvement effect on growth indexes such as the plant height, aboveground dry matter weight and leaf area of sunflowers. This is mainly due to the lack of the synergistic effect of carboxyl groups and trehalose on the biochar surface.

[0084] As can be seen from the data of Example 2 and Comparative Example 4 in Table 1, the post-wrapping of biochar with decomposed cow dung can significantly improve growth indexes such as the plant height, aboveground dry matter weight and leaf area of sunflowers. This is mainly because the decomposed cow dung contains a large amount of organic matter resources. On the one hand, it improves the activity of Bacillus amyloliquefaciens in the biochar, and on the other hand, it provides a large amount of organic matter for the soil, which helps to improve the soil structure and fertility and increase the diversity of soil microorganisms.

[0085] Those of ordinary skill in the art should understand that the discussion of any above embodiment is only exemplary 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 can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above, which are not provided in detail for the sake of brevity.

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 step (4), the ratio of trehalose-modified biochar to bacterial suspension is 4-6 g: 1.5-2.5 mL; 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; The concentration of the calcium chloride solution in step (4) is 4wt%-6wt%.

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: 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.