Bacterium-containing compound fertilizer and preparation method thereof

Abstract

The invention discloses a bacterium-containing compound fertilizer and a preparation method thereof, and belongs to the technical field of microbial fertilizers. According to the method, nitrogen-fixing bacteria, phosphate solubilizing bacteria and biocontrol bacteria are proportioned to form a compound bacteria solution, and humic acid and L-glutamic acid are added as metabolism synergists, so that the compound bacteria solution uniformly covers the surfaces of fertilizer particles. According to the preparation method of the bacterium-containing compound fertilizer provided by the invention, most of microorganisms in fermentation liquor and beneficial products generated by metabolism of the microorganisms are reserved in a liquid adding manner, and the bacteria-containing compound fertilizer can quickly play a role in soil; the compound bacteria liquid is added in an atomized form, so that the uniformity of bacteria adding is ensured, and the consistency of the effect of a fertilizer product is improved; the method is simple to operate, easy to implement and suitable for various compound fertilizer production processes.

Description

Technical Field

[0001] The present invention relates to the technical field of microbial fertilizers, and in particular to a bacteria-containing compound fertilizer and a preparation method thereof. Background Art

[0002] Microbial fertilizers are a type of fertilizer product that utilizes the life activities of microorganisms to achieve specific fertilizer effects on crops. Through these activities, microbial fertilizers can enhance soil fertility, improve soil structure, stimulate crop growth and development, enhance crop quality, and strengthen plant resistance to diseases, pests, and stress. They also reduce the use of chemical fertilizers and increase fertilizer utilization.

[0003] Common methods of adding bacteria to fertilizers include solid and liquid addition. While solid addition introduces low moisture into the inoculant, thus not affecting the existing production process, the dried inoculant retains only spores, resulting in a loss of beneficial metabolites. Furthermore, uneven addition affects the consistency of the fertilizer's effectiveness. In contrast, liquid addition maximizes the retention of microorganisms and their metabolites in the fermentation broth, and allows for uniform addition through atomization, reducing the overall amount of inoculant added and introducing less moisture, without compromising the product's commercial quality.

[0004] However, although the existing liquid addition technology has significant advantages, there is still room for improvement in the long-term maintenance of strain activity, adaptability in different environments and optimization of process details. Summary of the Invention

[0005] The purpose of the present invention is to provide a bacteria-containing compound fertilizer and a preparation method thereof. The method uniformly coats the functional strains on the surface of the compound fertilizer particles by liquid addition, further retains the microorganisms in the fermentation liquid and the beneficial products produced by their metabolism, improves the fertilizer utilization rate, enhances the disease resistance and stress resistance of crops, and reduces the use of chemical fertilizers.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: In one aspect, the present invention provides a method for preparing a bacterial compound fertilizer, comprising the following steps: (1) Mix the nitrogen-fixing bacteria solution, phosphate-dissolving bacteria solution and biocontrol bacteria solution, add deionized water to adjust the total concentration of live bacteria in the composite bacteria solution, and then add a metabolic enhancer; (2) mixing glycerol, seaweed extract and sodium carboxymethyl cellulose as a protective agent, and adding the mixture to the composite bacterial solution obtained in step (1); (3) In the compound fertilizer coating section, the compound bacterial solution is evenly sprayed on the surface of the fertilizer particles in a secondary atomization manner through a nozzle, and the bacteria-containing compound fertilizer is obtained after coating.

[0007] Preferably, the mixing ratio of the nitrogen-fixing bacteria solution, the phosphate-dissolving bacteria solution and the biocontrol bacteria solution in step (1) is 2:1:1 based on the number of viable bacteria, and the total viable bacteria concentration of the adjusted composite bacteria solution is 1×10 9 CFU / mL; Preferably, the metabolic enhancer in step (1) is a composite solution of humic acid and L-glutamic acid, and the added amount accounts for 2.5%-5% of the total mass of the composite bacterial solution, wherein the mass ratio of humic acid to L-glutamic acid is 4:1.

[0008] Preferably, the amount of the protective agent added in step (2) accounts for 3%-5% of the mass of the composite bacterial solution, and the mass ratio of glycerol, seaweed extract and sodium carboxymethyl cellulose is 2:2:1.

[0009] Preferably, in step (3), the secondary atomization is specifically as follows: in the first stage atomization, the composite bacterial liquid is dispersed into primary droplets with a diameter of 100-200 μm through a pressure nozzle, and preliminarily mixed with the coating oil preheated to 25-30°C; in the second stage atomization, the mixed liquid obtained by the first stage atomization is broken into fine droplets of 50-80 μm by the high-pressure air flow provided by the nozzle, and the droplets are in countercurrent contact with the fertilizer particles in the rotating drum to increase the coverage of the composite bacterial liquid on the particle surface.

[0010] More preferably, in step (3), the pressure of the first-stage atomizing nozzle is 0.1-0.3 MPa, the pressure of the second-stage atomizing nozzle is 0.3-0.5 MPa, and the temperature of the composite bacterial liquid is maintained at 25-30°C.

[0011] On the other hand, the present invention provides a bacterial compound fertilizer prepared according to the above preparation method, wherein each gram of fertilizer contains an effective number of living bacteria ≥ 5×10 7 CFU, the uniformity of composite bacterial liquid coverage on the surface of fertilizer particles is ≥90%, and the thickness of the coating layer is 20-50μm.

[0012] Compared with the prior art, the present invention has the following beneficial effects: (1) Retaining beneficial metabolites: The method for preparing the bacterial compound fertilizer provided by the present invention retains most of the microorganisms in the fermentation liquid and the beneficial products produced by their metabolism through liquid addition, and can quickly play a role in the soil; the compound bacterial liquid is added in the form of atomization, which ensures the uniformity of the added bacteria and improves the consistency of the fertilizer product effect; the method is simple to operate and easy to implement, and is applicable to a variety of compound fertilizer production processes.

[0013] (2) Improve fertilizer utilization rate: The method for preparing bacterial compound fertilizer provided by the present invention can improve soil fertility, improve soil structure, and increase fertilizer utilization rate by adding functional strains; it can also enhance the stress resistance of crops and reduce the use of chemical fertilizers. DETAILED DESCRIPTION

[0014] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0015] The sources of some raw materials used in the examples and comparative examples are as follows: The nitrogen-fixing bacteria were selected from Herrenknecht ® Round brown nitrogen-fixing bacteria commercial products; phosphate-solubilizing bacteria selected from Herrenknecht ® Aerobic phosphorus removal bacteria products; biocontrol bacteria selected from Huaneng ® Bacillus subtilis products; seaweed extracts are produced by Wuhan Guanying Biotechnology Co., Ltd.; compound fertilizers are produced by Yangfeng ® Supreme TM 17-11-15 compound fertilizer. Example 1

[0016] A method for preparing a bacteria-containing compound fertilizer comprises the following steps: (1) Add 10 mL of 2×10 9 CFU / mL nitrogen-fixing bacteria solution, 10mL of 1×10 9 CFU / mL phosphate-solubilizing bacteria solution and 10mL of 1×10 9 CFU / mL biocontrol bacterial solution was mixed to form a composite bacterial solution, and 10 mL of deionized water was added to adjust the total concentration of viable bacteria to 1×10 9 CFU / mL, and then 1.5g of metabolic enhancer prepared by humic acid and L-glutamic acid in a mass ratio of 4:1 was added; (2) Mix 0.64 g of glycerol, 0.64 g of seaweed extract and 0.32 g of sodium carboxymethyl cellulose as a protective agent, and add it to the composite bacterial solution obtained in step (1); (3) In the compound fertilizer coating section, the composite bacterial solution is evenly sprayed onto the surface of the fertilizer particles through a nozzle in a two-stage atomization manner: in the first stage of atomization, the composite bacterial solution maintained at a temperature of 27°C is dispersed into primary droplets with a diameter of 100-200 μm through a 0.2 MPa pressure nozzle, and is initially mixed with the coating oil preheated to 27°C; in the second stage of atomization, the mixed solution obtained by the first stage of atomization is broken into fine droplets of 50-80 μm by a 0.4 MPa high-pressure airflow provided by the nozzle. The droplets come into countercurrent contact with the fertilizer particles in a rotating drum, thereby increasing the coverage rate of the composite bacterial solution on the particle surface. After coating, the bacterial compound fertilizer is obtained. Example 2

[0017] A method for preparing a bacteria-containing compound fertilizer comprises the following steps: (1) Add 10 mL of 2×10 9 CFU / mL nitrogen-fixing bacteria solution, 10mL of 1×10 9 CFU / mL phosphate-solubilizing bacteria solution and 10mL of 1×10 9CFU / mL biocontrol bacterial solution was mixed to form a composite bacterial solution, and 10 mL of deionized water was added to adjust the total concentration of viable bacteria to 1×10 9 CFU / mL, and then 1.0 g of a metabolic enhancer prepared from humic acid and L-glutamic acid at a mass ratio of 4:1 was added; (2) Mix 0.48 g of glycerol, 0.48 g of seaweed extract and 0.24 g of sodium carboxymethyl cellulose as a protective agent, and add it to the composite bacterial solution obtained in step (1); (3) In the compound fertilizer coating section, the composite bacterial solution is evenly sprayed onto the surface of the fertilizer particles through a nozzle in a two-stage atomization manner: in the first stage of atomization, the composite bacterial solution maintained at a temperature of 25°C is dispersed into primary droplets with a diameter of 100-200 μm through a 0.1 MPa pressure nozzle, and is initially mixed with the coating oil preheated to 25°C; in the second stage of atomization, the mixed solution obtained by the first stage of atomization is broken into fine droplets of 50-80 μm by a 0.3 MPa high-pressure airflow provided by the nozzle. The droplets are countercurrently contacted with the fertilizer particles in a rotating drum to increase the coverage rate of the composite bacterial solution on the particle surface. After coating, the bacterial compound fertilizer is obtained. Example 3

[0018] A method for preparing a bacteria-containing compound fertilizer comprises the following steps: (1) Add 10 mL of 2×10 9 CFU / mL nitrogen-fixing bacteria solution, 10mL of 1×10 9 CFU / mL phosphate-solubilizing bacteria solution and 10mL of 1×10 9 CFU / mL biocontrol bacterial solution was mixed to form a composite bacterial solution, and 10 mL of deionized water was added to adjust the total concentration of viable bacteria to 1×10 9 CFU / mL, and then 2.0 g of a metabolic enhancer prepared from humic acid and L-glutamic acid at a mass ratio of 4:1 was added; (2) Mix 0.8 g of glycerol, 0.8 g of seaweed extract and 0.4 g of sodium carboxymethyl cellulose as a protective agent, and add it to the composite bacterial solution obtained in step (1); (3) In the compound fertilizer coating section, the composite bacterial solution is evenly sprayed onto the surface of the fertilizer particles through a nozzle in a two-stage atomization manner: in the first stage of atomization, the composite bacterial solution maintained at a temperature of 30°C is dispersed into primary droplets with a diameter of 100-200 μm through a 0.3 MPa pressure nozzle, and is preliminarily mixed with the coating oil preheated to 30°C; in the second stage of atomization, the mixed solution obtained by the first stage of atomization is broken into fine droplets of 50-80 μm by a 0.5 MPa high-pressure airflow provided by the nozzle. The droplets come into countercurrent contact with the fertilizer particles in a rotating drum, thereby increasing the coverage rate of the composite bacterial solution on the particle surface. After coating, the bacterial compound fertilizer is obtained.

[0019] Comparative Example 1 A method for preparing a bacteria-containing compound fertilizer comprises the following steps: (1) 10g of 2×10 9 CFU / g nitrogen-fixing bacteria powder, 10g of 1×10 9 CFU / g phosphate-solubilizing bacteria powder and 10mL of 1×10 9 CFU / g biocontrol fungus powder was mixed, and 2.25g of a metabolic enhancer prepared from humic acid and L-glutamic acid in a mass ratio of 4:1 was added; (2) Mix 0.64 g of glycerol, 0.64 g of seaweed extract and 0.32 g of sodium carboxymethyl cellulose as a protective agent, and add it to the mixed bacterial powder obtained in step (1); (3) In the compound fertilizer coating process, the mixed bacterial powder is directly mixed with the fertilizer particles to obtain a microbial compound fertilizer product.

[0020] Comparative Example 2 The difference from Example 1 is that step (2) is omitted.

[0021] The rest is the same as Example 1.

[0022] Comparative Example 3 The difference from Example 1 is that in step (1), only 20 mL of 2×10 9 CFU / mL nitrogen-fixing bacteria solution, add 20mL of deionized water to adjust the total concentration of viable bacteria to 1×10 9 CFU / mL.

[0023] The rest is the same as Example 1.

[0024] Test Case (1) The viable bacteria survival rate test was conducted on the finished fertilizer products obtained in Examples 1-3 and Comparative Examples 1-3: When the fertilizer preparation is completed, 10 g of sample is weighed and 90 mL of sterile saline (containing 0.1% Tween 80) is added to make 10 -1 After shaking for 30 minutes, press 10 -2 ~10 -8 A gradient dilution was performed, and 0.1 mL of the suspension at different dilutions was applied to a selective culture medium, wherein Axelrod's medium was used for nitrogen-fixing bacteria, PK medium was used for phosphate-solubilizing bacteria, and corresponding resistance medium was used for biocontrol bacteria. The suspension was cultured at 30°C for 72 hours, and the colony forming units (CFU) was counted and the colony forming units per milliliter of culture solution (CFU / mL) was calculated. The average viable bacterial survival rate of each group of the embodiment and the comparative example was calculated based on the theoretical viable bacterial concentration of the fertilizer.

[0025] (2) Metabolite retention rate test of the finished fertilizers prepared in Examples 1-3 and Comparative Examples 1-3: Upon completion of fertilizer preparation, 5 g of each fertilizer sample was weighed and added to 25 mL of sterile saline. After extraction with shaking for 1 hour, the sample was centrifuged at 200 rpm, and triplicate supernatants were collected for testing. For nitrogen-fixing bacteria, ammonium nitrogen content was determined using the indophenol blue colorimetric method; for phosphate-solubilizing bacteria, soluble phosphorus content was determined using the molybdenum antimony colorimetric method; and for biocontrol bacteria, IAA content was determined using the Salkowski colorimetric method.

[0026] The remaining fertilizer was sealed and stored at a constant temperature of 25°C. After one month, 5 g of samples were taken and the above steps were repeated to calculate the retention rate of the metabolite content after storage compared with the initial metabolite content.

[0027] (3) The finished fertilizers obtained in Examples 1-3 and Comparative Examples 2-3 were tested for coverage uniformity: Thirty granules were randomly selected from each group of fertilizer samples, soaked in the fluorescent dye 0.1% acridine orange for 10 minutes, rinsed with distilled water, and then dried. The fluorescence distribution on the granule surface was observed under a fluorescence microscope, and the image analysis software Image-ProPlus was used to calculate the percentage of fluorescence coverage area. The average and standard deviation of the coverage area of ​​the 30 fertilizer granules were statistically analyzed to calculate the coverage uniformity.

[0028] (4) The finished fertilizers obtained in Examples 1-3 and Comparative Examples 1-3 were subjected to a sustained-release cycle test: Take a glass column with a diameter of 5 cm and a height of 30 cm, lay 10 cm thick quartz sand on the bottom layer, fill the middle layer with 15 cm thick saline-alkali soil, place 5 g of fertilizer sample on the upper layer, and then cover the fertilizer with 5 cm of soil. Leach it with 50 mL of deionized water once a week, collect the leachate, and determine the number of viable bacteria and the content of metabolites in the leachate according to the test methods of experiments (1) and (2).

[0029] When the total concentration of viable bacteria in the leaching fluid is less than 10 3 When the CFU / mL and the metabolite content was less than 5% of the initial value, the experiment was stopped and the total leaching time was recorded as the sustained-release period.

[0030] (5) The finished fertilizers obtained in Examples 1-3 and Comparative Examples 1-3 were tested for yield increase in saline-alkali land: Seven experimental plots were set up in typical saline-alkali land, and the soil pH was adjusted to 8.5-9.5 and the conductivity to 2-4 dS / m. Six treatment groups were set up for Examples 1-3, Comparative Examples 1-3, and a blank group (only ordinary fertilizer was applied), with three plots in each group, each with an area of ​​20 m 2 , randomized block arrangement; The cotton variety "Jinken 1775" was selected as the test crop for sowing, with a row spacing of 50 cm and a plant spacing of 25 cm. The fertilizer application rate for each plot was uniformly 0.4 kg, and other field management practices remained consistent. After the crop matured, the cotton yield of the plot was measured, and the yield increase rate of Examples 1-3 and Comparative Examples 1-3 relative to the blank group was calculated.

[0031] The results of the above five tests are shown in Table 1.

[0032] Table 1 Microbial fertilizer performance test results Detection indicators Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Live bacteria survival rate 92.3% 89.7% 85.4% 41.2% 63.5% 75.6% Metabolite retention rate 96.5% 94.2% 88.7% 32.8% 71.4% 82.3% Coverage uniformity 93.4% 90.1% 87.6% / 78.9% 84.7% Sustained-release cycle 18 days 16 days 12 days 3 days 7 days 9 days Saline-alkali land yield increase rate 27.3% 24.6% 20.1% 8.2% 15.7% 18.4% As can be seen from Table 1, the microbial compound fertilizers prepared in Examples 1-3 exceeded the compound fertilizers prepared in Comparative Examples 1-3 in all indicators, proving that the microbial compound fertilizers provided in this application can improve soil fertility, improve soil structure, increase fertilizer utilization, and enhance crop resistance.

[0033] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0034] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a bacterial compound fertilizer, characterized in that: The following steps are involved: (1) Mix the nitrogen-fixing bacteria solution, phosphate-dissolving bacteria solution and biocontrol bacteria solution, add deionized water to adjust the total concentration of live bacteria in the composite bacteria solution, and then add a metabolic enhancer; (2) mixing glycerol, seaweed extract and sodium carboxymethyl cellulose as a protective agent, and adding the mixture to the composite bacterial solution obtained in step (1); (3) In the compound fertilizer coating section, the compound bacterial solution is evenly sprayed on the surface of the fertilizer particles in a secondary atomization manner through a nozzle, and the bacteria-containing compound fertilizer is obtained after coating.

2. The method for preparing the bacterial compound fertilizer according to claim 1, wherein: The mixing ratio of the nitrogen-fixing bacteria solution, the phosphate-dissolving bacteria solution and the biocontrol bacteria solution in step (1) is 2:1:1 based on the number of viable bacteria. The total concentration of viable bacteria after the composite bacteria solution is adjusted is 1×10 9 CFU / mL.

3. The method for preparing the bacterial compound fertilizer according to claim 1, wherein: The amount of the metabolic enhancer added in step (1) accounts for 2.5%-5% of the total mass of the composite bacterial solution.

4. The method for preparing the bacterial compound fertilizer according to claim 1, wherein: The metabolic enhancer in step (1) is a composite solution of humic acid and L-glutamic acid.

5. The method for preparing the bacterial compound fertilizer according to claim 4, wherein: The mass ratio of humic acid to L-glutamic acid in the metabolic enhancer is 4:

1.

6. The method for preparing the bacterial compound fertilizer according to claim 1, wherein: The mass ratio of glycerol, seaweed extract and sodium carboxymethyl cellulose in step (2) is 2:2:

1.

7. The method for preparing the bacterial compound fertilizer according to claim 1, wherein: The amount of the protective agent added accounts for 3%-5% of the mass of the composite bacterial liquid.

8. The method for preparing the bacterial compound fertilizer according to claim 1, wherein: The secondary atomization in step (3) is specifically as follows: in the first stage atomization, the composite bacterial solution is dispersed into primary droplets with a diameter of 100-200 μm through a pressure nozzle, and preliminarily mixed with the coating oil preheated to 25-30°C; in the second stage atomization, the mixed solution obtained by the first stage atomization is broken into fine droplets of 50-80 μm by the high-pressure air flow provided by the nozzle, and the droplets are in countercurrent contact with the fertilizer particles in the rotating drum to increase the coverage rate of the composite bacterial solution on the particle surface.

9. The method for preparing the bacterial compound fertilizer according to claim 8, characterized in that: In step (3), the pressure of the first-stage atomizing nozzle is 0.1-0.3 MPa, the pressure of the second-stage atomizing nozzle is 0.3-0.5 MPa, and the temperature of the composite bacterial liquid is maintained at 25-30°C.

10. A bacterial compound fertilizer, characterized in that: The bacterial compound fertilizer is prepared by the preparation method of any one of claims 1 to 9.