Preparation method of carbon-based fertilizer based on functional microorganisms, obtained product and application

Abstract

The invention belongs to the technical field of compositions containing microorganisms, and particularly relates to a preparation method of a carbon-based fertilizer based on functional microorganisms, an obtained product and application. The biochar is prepared from the straws, so that the physical and chemical properties of soil can be improved, soil acidification can be relieved, the enzyme activity can be improved, and the number of soil microorganisms can be increased. The straw biochar is used as a fertilizer synergistic carrier to prepare the biochar base fertilizer, and the biochar base fertilizer can effectively relieve the release speed of fertilizer nutrients in soil, reduce nutrient leaching loss and enhance water and fertilizer retention of soil, so that the fertilizer utilization rate is increased, and the problem of resource utilization of crop straws is solved; meanwhile, the problems of dust pollution and the like caused by only adopting the straw biochar are effectively solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of compositions containing microorganisms, and in particular relates to a method for preparing a carbon-based fertilizer based on functional microorganisms, and the obtained products and applications. Background Art

[0002] Straw mainly includes the stems, leaves and stalks left after crops mature, which contain a large amount of nitrogen, phosphorus, potassium and other trace elements. With the extensive use of agricultural inputs and the popularization of agricultural machinery, agricultural output has increased significantly. With the increase in the amount of straw, the reserve of crop straw is abundant, but the utilization efficiency is low. At present, the conventional treatment method is to return it to the field directly after crushing or directly burn it, which causes energy waste, accelerates greenhouse gas emissions and haze formation, and has a huge impact on the environment. The utilization rate of straw is not high and it does not improve the fertility of the soil much.

[0003] At present, in the agricultural production process, the amount of fertilizer applied is large but the utilization rate is low. The low fertilizer utilization rate and high fertilizer input are likely to cause soil, water, air and agricultural product pollution, and bring farmland problems such as soil compaction and reduced soil bulk density. In addition, the carbon pool deficit and microbial imbalance in the soil are also accelerating the deterioration of soil fertility. Fertilizer is an important agricultural carbon emission resource, and improving the utilization rate of fertilizer is an important task in the comprehensive green transformation of agricultural production. Summary of the invention

[0004] In view of the problems of low straw utilization rate, soil deterioration and the like in the prior art, the present invention provides a method for preparing carbon-based fertilizer based on functional microorganisms.

[0005] The present invention also provides carbon-based fertilizer based on functional microorganisms prepared by the above preparation method.

[0006] The present invention further provides the application of the carbon-based fertilizer based on functional microorganisms.

[0007] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: The present invention provides a method for preparing carbon-based fertilizer based on functional microorganisms, comprising the following steps: (1) drying the straw, crushing and screening it, and then carbonizing it to obtain straw biochar; (2) Select live Acinetobacter KJ-1 strains and inoculate them into NB liquid culture medium to culture the strains until the logarithmic growth phase to obtain seed solution; (3) Weigh the straw biochar and the immobilization medium, mix them and sterilize them, take the seed solution and inoculate it into the mixed solution containing the immobilization medium and the straw biochar to carry out immobilization culture, wash the fixed bacterial agent with NaCl solution, and the obtained sediment is the straw biochar with immobilized bacteria; (4) Add the straw biochar based on functional microorganisms to the auxiliary materials and mix them evenly to obtain the carbon-based fertilizer.

[0008] Furthermore, in step (1), the carbonization treatment conditions are: dry distillation carbonization in a closed oxygen-limited autoclave, a heating rate of 10°C / min, and pyrolysis at a temperature of 300°C-700°C for 2h.

[0009] Furthermore, in step (2), the live Acinetobacter KJ-1 was deposited in the General Microbiology Center of China National Microbiological Culture Collection Administration on September 17, 2020, with the deposit number CGMCC No.20664.

[0010] Furthermore, in step (2), the composition of the NB liquid culture medium is: peptone 10 g / mL, beef extract powder 3 g / mL, sodium chloride 5 g / mL; the number of strains in the seed liquid is 2-4×10 9 cfu / mL.

[0011] Furthermore, in step (2), the culturing is carried out at 180 rpm and 30°C.

[0012] Furthermore, in step (3), the ratio of the straw biochar to the immobilization medium is 0.75 g:45-50 mL; the composition of the immobilization medium is: sucrose 10 g / mL, beef cake 6 g / mL, yeast powder 2 g / mL, pH 7.0-7.2.

[0013] Furthermore, in step (3), the ratio of the straw biochar to the seed solution is 0.75 g:2.5 mL; and the immobilization culture is performed at 180 rpm and 30°C for 16-24 h.

[0014] Furthermore, in step (4), the carbon-based fertilizer comprises the following raw materials in parts by weight: 40 parts of straw biochar with immobilized bacteria, 10 parts of decomposed cow dung, 5 parts of peptone, 10 parts of ammonium sulfate, 5 parts of potassium nitrate, 5 parts of boric acid, and 1 part of sodium α-naphthyl acetate.

[0015] The present invention also provides a carbon-based fertilizer based on functional microorganisms prepared by the above preparation method.

[0016] The present invention also provides the use of the carbon-based fertilizer based on functional microorganisms in promoting plant growth.

[0017] The present invention uses straw to prepare biochar, which can improve soil physical and chemical properties, alleviate soil acidification, increase enzyme activity, and increase the number of soil microorganisms. Using straw biochar as a fertilizer synergistic carrier to make biochar-based fertilizer can effectively alleviate the release rate of fertilizer nutrients in the soil, reduce nutrient leaching loss, and enhance soil water and fertilizer retention, thereby improving fertilizer utilization, solving the problem of crop straw resource utilization, and effectively solving the dust pollution caused by using only straw biochar.

[0018] The beneficial effects of the present invention are: (1) The functional microorganism Acinetobacter KJ-1 provided by the present invention has the ability to produce siderophores, solubilize phosphate, and promote plant growth, and can be used to promote plant rhizosphere growth; (2) The straw biochar prepared by the present invention has a large surface area and microporous structure, and has strong hydrophilicity, which can provide a good growth microenvironment for microorganisms, thereby improving the growth of soil microorganisms; when the pore volume of the biochar is large, microorganisms are more likely to enter the pores of the biochar and utilize the nutrients therein, so biochar with a large pore volume is more conducive to the entry and growth of microorganisms with a smaller volume and a faster growth rate, and the biochar contains more carboxyl functional groups, which is more suitable as a microbial carrier; (3) The charcoal-based fertilizer prepared by the functional microorganisms immobilized on straw biochar can significantly improve soil permeability, loosen the soil, and increase soil fertility. After being applied to crop planting, it can increase the content of chlorophyll and the like in the crops and promote plant growth. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The electron scanning microscope photos (10,000 times) of straw-derived biochar at three different temperatures, A: calcined at 300℃ for 2h; B: calcined at 500℃ for 2h; C: calcined at 700℃ for 2h; Figure 2 is the water absorption rate and water absorption rate of straw biochar, where A: biochar water absorption rate; B: biochar water absorption rate; Figure 3 The infrared spectra of three types of straw biochars; Figure 4 It is the determination of the characteristics of live Acinetobacter KJ-1, among which A: siderophore production ability determination; B: phosphate solubilization ability determination; B: IAA synthesis ability determination; Figure 5 To determine the growth-promoting effect of live Acinetobacter KJ-1 on Arabidopsis thaliana; Figure 6The influence of various factors on biochar immobilized bacteria, including: A: immobilization time (h); B: immobilization temperature (℃); C: initial pH of immobilization medium; D: carrier dosage in immobilization medium (g / L). DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0021] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0022] Live Acinetobacter KJ-1 was deposited in the General Microbiology Center of China Microorganism Culture Collection Administration on September 17, 2020, with the culture collection number CGMCC No. 20664. This strain has been recorded in patent ZL202110162231.2.

[0023] Unless otherwise specified, the experimental methods described in the following embodiments are all conventional methods; the reagents and materials described are all commercially available unless otherwise specified.

[0024] The biochar prepared by the present invention is made of corn stalks, and stalks produced by other crops can also be used as raw material sources for biochar.

[0025] Example 1 Preparation and electron microscopic characterization of corn straw biochar After drying, the straw is crushed and sieved, and the dried straw is loaded into a quartz boat for the preparation of biochar. Among them, the carbonization conditions are: dry distillation carbonization, closed oxygen-limited autoclave carbonization, heating rate 10℃ / min, pyrolysis at 300℃, 500℃, and 700℃ for 2h respectively. The carbon yield is calculated according to the following public statement, and the results are shown in Table 1.

[0026]

[0027] m1: mass of biochar and quartz boat, g; m2: quartz boat mass, g; m: straw mass, g.

[0028] Table 1: Carbon yield of straw biochar (%)

[0029] As the temperature increases, the carbon yield of biochar using straw as raw material for high-temperature oxygen-free calcination gradually decreases (Table 1). The biochar yields at 300℃, 500℃, and 700℃ are 40.00%, 33.40%, and 27.40%, respectively.

[0030] Scanning electron microscopy was used to observe the surface structure of straw biochar prepared at three different temperatures. Figure 1 As shown in the figure, compared with the three biochars, the surface of CS700 is more severely damaged, while the surface of CS300 is relatively intact; after 10k times magnification, the surface of CS300 is smoother and flatter, but the surfaces of CS500 and CS700 are relatively rough, loose and porous, and have more blocky substances; under the electron microscope, it can be clearly seen that the pore structure is evenly distributed on the surface of the biochar, and the pore size and pore number are relatively obvious. In this experiment, CS500 and CS700 have more pore structures, which have better adsorption effects than CS300. At the same time, the diffusion process in the adsorbent particles is easier to carry out, which improves the adsorption efficiency in the pores.

[0031] Example 2 Physicochemical Characterization Analysis of Straw Biochar Various characterization analyses were performed on the straw biochar obtained in Example 1. The main analyses were elemental composition analysis, specific surface area and pore measurement, infrared spectrum measurement, water absorption capacity measurement, and pH measurement.

[0032] (1) Biochar pH and elemental analysis Take 1g of the prepared straw biochar in a 150 mL Erlenmeyer flask and dilute it with 100 mL of deionized water to prepare a biochar suspension. Use an ultrasonic machine to sonicate for 1 h until the soluble components of the biochar are completely dissolved in the water, and then use a pH meter to measure its pH value, which is the pH value of the biochar.

[0033] The prepared biochars at three temperatures of 300℃, 500℃ and 700℃ were placed in an elemental analyzer for elemental analysis of biochar. When the instrument was adjusted to a helium pressure of 0.121MPa, a flow rate of 200mL min-1, an oxygen pressure of 0.2MPa, and an oxygen flow rate of 13~14mL min-1, the CHNS mode was used to determine the percentage of C, H, and N elements in the biochar when the combustion furnace temperature reached 1150℃ and the reduction furnace temperature reached 850℃, and the percentage of O element was measured using the O mode. Each biochar sample was measured three times and the average value was calculated, thereby obtaining the content of each element in the three biochars and the atomic ratios of (N+O) / C, H / C, (C+H) / O, and O / C of the organic matter components. The results are shown in Table 2. As the temperature increases, the pH and the mass and atomic ratio of each element show regular changes.

[0034] Table 2: pH value, elemental mass composition and atomic ratio of biochar

[0035] (2) Analysis of biochar pore structure The specific surface area, nitrogen adsorption micropores, mesopore distribution, and pore volume of biochar were measured using a multi-station extended automatic rapid specific surface analyzer. The results are shown in Table 3. Among them, CS500 has the smallest specific surface area, total pore volume, and average pore size, and its micropore size is the largest. There is no significant difference in the micropore volume between CS300 and CS500, and CS700 has the largest micropore volume.

[0036] Table 3: Characterization analysis of biochar such as specific surface area and total pore volume

[0037] (3) Analysis of water absorption of biochar The water absorption of biochar under constant temperature and humidity conditions was determined by gravimetric method. Figure 2 The curves showing the change of water absorption rate and water absorption rate of straw biochar over time. The water absorption rate of the three types of straw biochar has the same trend over time ( Figure 2 A), after a certain period of time, the water absorption process reaches equilibrium. Figure 2 B shows that the straw biochar has a faster water absorption rate at the beginning of water absorption, and then the rate decreases rapidly, and then approaches zero after a slow decrease and remains unchanged.

[0038] (4) Infrared spectroscopy analysis of biochar Fourier transform infrared spectroscopy was used to analyze the functional groups on the surface of biochar. Figure 3 The straw biochar was found to be at 2929 cm -1 and 2922 cm -1 There are peaks on the left and right. These characteristic peaks belong to the asymmetric stretch absorption peaks of (-CH2) with smaller intensity values. It can be seen that CS300 is stronger than CS500 and CS700. At 1616 cm -1 and 1620 cm -1 The peaks on the left and right are caused by the stretching vibration of the hydroxyl group (-OH) and the ester group (C=O) in the ester. It can be clearly seen that CS300 is stronger than CS500 and CS700. -1 The characteristic peaks on the left and right are the stretching vibrations of the carboxyl group (-COOH). The peak values ​​of CS300 and CS500 are similar, while the intensity of CS700 is smaller, which proves that the functional groups in the biochar are destroyed when the temperature reaches 700°C.

[0039] Three types of straw biochar were obtained by high-temperature oxygen-free calcination, and the biochar characterization analysis was carried out. Subsequently, these three types of biochar were selected for the preparation of composite carbon-based fertilizer.

[0040] Example 3 Effect of live Acinetobacter in promoting plant growth Live Acinetobacter KJ-1 was deposited in the General Microbiology Center of China Microorganism Culture Collection Administration on September 17, 2020, with the culture collection number CGMCC No.20664.

[0041] (1) Determination of the ability of strains to produce siderophores Pick a single colony of the test strain and inoculate it into NB liquid medium and shake and culture until OD 600 =0.8, 3 μL of bacterial solution was inoculated on CAS solid medium and cultured at 30 ℃ for 7 days, and the colonies were observed to see whether there was an orange halo around them. The larger the halo, the stronger the ability to produce iron carriers. The test was repeated 3 times. The results showed that the ability of this bacterium to produce iron carriers was the strongest compared with other test strains ( Figure 4 A).

[0042] (2) Determination of the phosphate solubilization ability of strains Pick a single colony of the test strain and inoculate it into NB liquid medium, shake and culture until OD 600 =0.8, 3 μL of bacterial solution was inoculated on PVK inorganic phosphorus medium and placed upside down in an incubator at 30 ℃ for 7 days. The changes around the bacteria on the plate were observed. Transparent circles appeared around the colonies, indicating that the strain had the ability to solubilize phosphate. The size of the transparent circle can be used as a sign of the strength of solubilization. The larger the transparent circle, the stronger the ability of the strain to solubilize phosphate. In this experiment, strain KJ-1 had a strong ability to solubilize phosphate ( Figure 4 B).

[0043] The above-mentioned CAS solid culture medium and PVK inorganic phosphorus culture medium were purchased from Beijing Coolbo Technology Co., Ltd.

[0044] (3) Determination of indoleacetic acid (IAA) synthesis capacity The test strain was inoculated into NB liquid medium, cultured with shaking for 24 h, centrifuged at 8000 rpm, rinsed with sterile water, and adjusted OD 600 =0.8, 200 μL of bacterial solution was inoculated into 4 mL (containing 1% 200 mg / L L-tryptophan) NB liquid medium, and the medium without bacterial solution was used as blank control. Each treatment was repeated 3 times, and the culture was shaken at 28 ℃ and 180 rpm for 4 days. After the culture, the bacterial solution was centrifuged at 8000 rpm for 10 min, 1 mL of the supernatant was taken, and an equal volume of Salkowski colorimetric agent was added. It was kept away from light for 30 min and its color change was observed. If the color turns red, it is considered to have the ability to produce IAA. The darker the color, the stronger the IAA synthesis ability. The results showed that strain KJ-1 has a strong ability to produce IAA ( Figure 4 C).

[0045] Preparation of the above-mentioned Salkowski colorimetric solution: Mix 50 mL of 35% HClO4 and 1 mL of 0.5 mol / L FeCl3, place in a brown bottle, and prepare before use.

[0046] (4) Determination of the growth-promoting ability of the strain on Arabidopsis thaliana Seed disinfection: Select Arabidopsis wild type Columbia-0 (Col-0): disinfect with 2.5% sodium hypochlorite for 3 minutes while shaking continuously, rinse with sterile water 3 times, then disinfect with 70% alcohol for 3 minutes, rinse the seeds with sterile water, rinse for 3 minutes each time, and wash 3 times.

[0047] Vernalization of Arabidopsis: Use a sterile pipette tip to spot the sterilized seeds at 1 / 3 of the 0.2M MS solid culture medium. Place 8 seeds on each plate. After drying, seal the plate and place it in a 4°C refrigerator for vernalization for two days.

[0048] Preparation of bacteria: Place the bacteria in 10 ml NB liquid and culture overnight. The next day, centrifuge the bacteria at 4°C and 7000 rpm, remove the supernatant, and keep only the bacteria. Add appropriate amount of sterile water to suspend the bacteria until OD 600 The value is 1, and 40ul is pipetted onto 1 / 2 of the plate. The culture dish is placed in a growth chamber at 22-25°C and cultured vertically with a light photoperiod of 16 hours and a dark photoperiod of 8 hours. Observe, measure and take photos for 10 days.

[0049] Biomass determination: density (density = number of lateral roots / main root length), fresh weight (select 6 plants with the same growth in each plate and weigh them) Results Figure 5 From the picture, we can directly see that the leaf area of ​​the aboveground part of Arabidopsis treated with bacteria is significantly larger than that of ck, and the lateral roots of the underground part treated with bacteria are dense and significantly longer. This shows that strain KJ-1 has a significant growth-promoting effect on Arabidopsis.

[0050] Example 4 Preparation of biochar-immobilized bacteria (1) Pick live Acinetobacter KJ-1 from the plate and inoculate it into NB liquid medium. Cultivate the bacteria at 180 rpm and 30 °C until the logarithmic growth phase. The number of bacteria in the bacterial suspension is about 2-4×10 9 cfv / mL, this is the seed solution.

[0051] (2) Weigh a certain amount of biochar (0.75 g) and mix it with 47.5 mL of microbial immobilization culture medium, sterilize it at 121 °C for 20 min, take 2.5 mL of seed solution and inoculate it into a conical flask containing microbial immobilization culture medium and biochar, and fix it at 180 rpm and 30 °C for 24 h. The fixed bacterial agent was washed with 0.9% sterile NaCl solution, and the process was repeated three times. The resulting sediment was the immobilized strain.

[0052] The number of microorganisms fixed on biochar was calculated by plate counting method. After the fixed microbial inoculant was centrifuged, it was washed three times with sterile 0.9% NaCl solution, and finally 30mL of sterile 0.9% NaCl solution was added. The ultrasonic crusher was used at a power of 40%, and the ultrasonic was performed for 1 second every 3 seconds for 10 minutes to remove the bacteria on the biochar. After the ultrasonic was completed, the suspension in the 5mL centrifuge tube was diluted into 6 gradients, and 0.2mL of the last gradient solution was poured into the plate, and then poured into NB solid culture medium. The number of colonies was calculated after culturing for 2 days. The results showed that the fixation capacity of the three types of straw biochar for live Acinetobacter KJ-1 was: CS500>CS300>CS700.

[0053] NB liquid medium (g / mL): peptone 10g, beef extract powder 3g and sodium chloride 5g NB solid medium (g / mL): peptone 10g, beef extract powder 3g, sodium chloride 5g, agar 15g Microbial immobilization culture medium (g / mL): sucrose 10, beef extract 5, yeast powder 4, pH 7.0-7.2 Example 5 Optimization of biochar immobilization conditions Taking CS300 as the test object, the single factor fixation conditions of the biochar immobilized bacteria in Example 4 were explored, mainly focusing on the effects of biochar dosage, immobilization time, immobilization temperature, and initial pH value of the immobilization medium. The results are shown in Figure 6 It was found that the immobilization conditions were controlled as follows: initial pH value at 7.0-7.8, immobilization temperature at 20-33°C, immobilization time at 16-24h, carrier dosage at 10-25g / L, and the optimal immobilization conditions were initial pH 7.5, culture temperature at 30°C, immobilization time at 20h, and carrier dosage at 15g.

[0054] Example 6 Preparation of carbon-based fertilizer A carbon-based fertilizer based on functional microorganisms, whose raw materials are mainly composed of 40 parts of straw biochar of immobilized bacteria (live Acinetobacter KJ-1), 10 parts of decomposed cow dung, 5 parts of peptone, 10 parts of ammonium sulfate, 5 parts of potassium nitrate, 5 parts of boric acid and 1 part of sodium α-naphthylacetate, calculated by weight.

[0055] The straw biochar is obtained by dehydrating straw, crushing it, screening it, and calcining it at 300° C. for 2 hours without oxygen. Functional microorganisms are immobilized on the obtained biochar to finally obtain biochar-based fertilizer based on functional microorganisms.

[0056] Example 7 Preparation of carbon-based fertilizer A carbon-based fertilizer based on functional microorganisms, whose raw materials are mainly composed of 40 parts of straw biochar of immobilized bacteria (live Acinetobacter KJ-1), 10 parts of decomposed cow dung, 5 parts of peptone, 10 parts of ammonium sulfate, 5 parts of potassium nitrate, 5 parts of boric acid and 1 part of sodium α-naphthylacetate, calculated by weight.

[0057] The straw biochar is obtained by dehydrating straw, crushing it, screening it, and calcining it at 500° C. for 2 hours without oxygen. Functional microorganisms are immobilized on the obtained biochar to finally obtain biochar-based fertilizer based on functional microorganisms.

[0058] Example 8 Preparation of carbon-based fertilizer A carbon-based fertilizer based on functional microorganisms, whose raw materials are mainly composed of 40 parts of straw biochar of immobilized bacteria (live Acinetobacter KJ-1), 10 parts of decomposed cow dung, 5 parts of peptone, 10 parts of ammonium sulfate, 5 parts of potassium nitrate, 5 parts of boric acid and 1 part of sodium α-naphthylacetate, calculated by weight.

[0059] The straw biochar is obtained by dehydrating the straw, crushing it, screening it, and calcining it at 700° C. for 2 hours without oxygen. Functional microorganisms are immobilized on the obtained biochar to finally obtain biochar-based fertilizer based on functional microorganisms.

[0060] Effect Example 1 The effects of the biochar-based fertilizers prepared in Examples 6-8 were verified as follows: The test site is Jinan Luqing Ecological Vegetable Planting Center, mainly for cucumber growth testing. The greenhouse is fully ventilated, shaded and rainproof, with insect-proof nets, and good natural factors such as light, temperature, humidity, and ventilation. The soil is neutral to slightly alkaline, with a deep tillage layer and good water and fertilizer retention.

[0061] Test variety: Cucumber Jinlu 21-10 Experimental design: The experiment used no biochar-based fertilizer as a blank control, and used decomposed cow dung and biochar calcined at 500℃ (SC500) as positive controls. The three biochar-based fertilizers were tested in the field. There were 6 treatments in total, each of which was repeated three times. The experimental greenhouse was divided into 18 plots, each of which was about 10m 2 Each treated fertilizer was applied as base fertilizer at a rate of 100 kg / mu. When applying base fertilizer, the soil surface was plowed to a depth of 20 cm. Other planting management methods such as planting density, irrigation, and pesticide application were carried out in accordance with the existing conventional management methods of greenhouses.

[0062] Observation and Recording: The growth of cucumbers and the physical and chemical properties of the soil were tested at different times after sowing. The growth of cucumbers mainly measured the length and width of the third leaf, the total number of leaves and the plant height.

[0063] Test results: Table 4 shows the growth of cucumber seedlings one month after sowing. It can be seen from the table that adding various carbon-based fertilizers, biochar and decomposed cow dung to the soil has a certain effect on plant growth compared with the control. Carbon-based fertilizers prepared by straw biochar calcined at different high temperatures have improved various indicators compared with SC500 alone, especially in terms of plant height. There is a significant difference between carbon-based fertilizer 500 and SC500, and compared with decomposed cow dung, there is an improvement, but the difference is not significant.

[0064] Table 4: Growth of cucumbers one month after sowing

[0065] Note: Different capital letters indicate significant differences at the 0.05 level.

[0066] Effect Example 2 The effects of the biochar-based fertilizers prepared in Examples 6-8 were verified as follows: The test site is Jinan Luqing Ecological Vegetable Planting Center, mainly for cucumber growth testing. The greenhouse is fully ventilated, shaded and rainproof, with insect-proof nets, and good natural factors such as light, temperature, humidity, and ventilation. The soil is neutral to slightly alkaline, with a deep tillage layer and good water and fertilizer retention.

[0067] The experimental design and treatment are the same as those in Example 1.

[0068] Index determination: Conventional methods were used to determine the soil organic carbon content, total nitrogen content, available phosphorus content and available potassium content, and to detect the effects of different treatments on the physical and chemical properties of the soil.

[0069] Table 5 Determination of soil physical and chemical properties after 30D treatment with different fertilizers. It can be seen from the table that after 30D treatment with different fertilizers, compared with soil without fertilizer application, each property has been improved to varying degrees. In particular, the carbon-based fertilizer based on functional microorganisms prepared in Examples 4-7, organic matter, total nitrogen, total phosphorus, total potassium, available nitrogen, available phosphorus and available potassium are significantly higher than those of biochar and decomposed cow dung alone, indicating that the carbon-based fertilizer obtained in this example, especially the carbon-based fertilizer 500, can increase soil fertility to a certain extent.

[0070] Table 5: Determination of soil physical and chemical properties after 30 days of treatment with different fertilizers

[0071] Note: Different capital letters indicate significant differences at the 0.05 level.

Claims

1. A method for preparing carbon-based fertilizer based on functional microorganisms, characterized in that: The following steps are involved: (1) drying the straw, crushing and screening it, and then carbonizing it to obtain straw biochar; (2) Select live Acinetobacter KJ-1 strains and inoculate them into NB liquid culture medium to culture the strains until the logarithmic growth phase to obtain seed solution; (3) Weigh the straw biochar and the immobilization medium, mix them and sterilize them, take the seed solution and inoculate it into the mixed solution containing the immobilization medium and the straw biochar to carry out immobilization culture, wash the fixed bacterial agent with NaCl solution, and the obtained sediment is the straw biochar with immobilized bacteria; (4) Add the straw biochar based on functional microorganisms to the auxiliary materials and mix them evenly to obtain the carbon-based fertilizer.

2. The method for preparing carbon-based fertilizer based on functional microorganisms according to claim 1, characterized in that: In step (1), the carbonization treatment conditions are: dry distillation carbonization in a closed oxygen-limited autoclave, a heating rate of 10°C / min, and pyrolysis at a temperature of 300°C-700°C for 2h.

3. The method for preparing carbon-based fertilizer based on functional microorganisms according to claim 1 or 2, characterized in that: In step (2), the live Acinetobacter KJ-1 was deposited in the General Microbiology Center of China Microorganism Culture Collection Administration on September 17, 2020, with the deposit number CGMCC No.20664.

4. The method for preparing carbon-based fertilizer based on functional microorganisms according to claim 1, characterized in that: In step (2), the composition of the NB liquid culture medium is: peptone 10 g / mL, beef extract powder 3 g / mL, sodium chloride 5 g / mL; the number of strains in the seed liquid is 2-4×10 9 cfu / mL.

5. The method for preparing carbon-based fertilizer based on functional microorganisms according to claim 4, characterized in that: In step (2), the culturing is carried out at 180 rpm and 30°C.

6. The method for preparing carbon-based fertilizer based on functional microorganisms according to claim 1, characterized in that: In step (3), the ratio of the straw biochar to the immobilization medium is 0.75 g:45-50 mL; the composition of the immobilization medium is: sucrose 10 g / mL, beef cake 6 g / mL, yeast powder 2 g / mL, pH 7.0-7.

2.

7. The method for preparing carbon-based fertilizer based on functional microorganisms according to claim 1 or 6, characterized in that: In step (3), the ratio of the straw biochar to the seed solution is 0.75 g:2.5 mL; the immobilization culture is performed at 180 rpm and 30°C for 16-24 h.

8. The method for preparing carbon-based fertilizer based on functional microorganisms according to claim 1, characterized in that: In step (4), the carbon-based fertilizer includes the following raw materials in parts by weight: 40 parts of straw biochar with immobilized bacteria, 10 parts of decomposed cow dung, 5 parts of peptone, 10 parts of ammonium sulfate, 5 parts of potassium nitrate, 5 parts of boric acid, and 1 part of sodium α-naphthylacetate.

9. A carbon-based fertilizer based on functional microorganisms prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the carbon-based fertilizer based on functional microorganisms as claimed in claim 9 in promoting plant growth.

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