A microbial compound fertilizer and its preparation method and application

Abstract

The present invention discloses a microbial composite fertilizer and its preparation method and application, belonging to the field of agricultural microbial technology. The microbial composite fertilizer is a wall material made of a mixture of hydrogel and fertilizer, and a composite porous carrier is used to load the composite microorganisms and then cross-linked and coated to form a core material, which is formed by coating the core material with the wall material; the core material is a carbon-based porous carrier and a modified sepiolite, which are both loaded with composite microorganisms and then cross-linked to form, and the carbon-based porous carrier is formed by modifying a mixture of sawdust and coconut chaff through a hydrothermal reaction to form a porous carrier. The present invention uses a carbon-based porous carrier and a modified sepiolite to load composite microorganisms, then cross-links and coats them, and then coats them again with a hydrogel, which has the dual effects of water retention and fertilizer slow release, while improving the activity and storage stability of the composite microorganisms and increasing the utilization rate of the composite microorganisms.

Description

Technical Field

[0001] The present invention relates to the field of agricultural microbial technology, and more specifically to a microbial compound fertilizer and a preparation method and application thereof. Background Art

[0002] Agricultural fertilizers include chemical fertilizers and microbial fertilizers. Microbial fertilizers refer to products containing specific living microorganisms used in agricultural production, which are essentially different from traditional chemical fertilizers and organic fertilizers. Microbial fertilizers are made by mixing microbial agents and microbial fertilizer formulas. Through the life activities of the microorganisms contained in them, they increase the supply of crop nutrients or promote crop growth, thereby increasing crop yields, improving the quality of agricultural products and the agricultural ecological environment. Microbial fertilizers can not only increase crop yields, improve the quality of agricultural products, and improve soil fertility, but also reduce the use of chemical fertilizers. They have low production costs, are easy to use, improve the soil environment, and do not pollute the environment. After application, they not only increase production, but also improve the quality of agricultural products and reduce the use of chemical fertilizers.

[0003] Due to the reasons of strains and ingredient ratio, the quality of microbial fertilizers in the market is uneven, and some problems have occurred in production and application, mainly the effective bacteria count does not meet the standard, and the effect of improving soil performance and increasing agricultural product yield in actual application is not ideal. The effective live bacteria count in microbial fertilizers is an important indicator of product quality. If the effective live bacteria count does not meet the standard, the product quality cannot be guaranteed, and the reflected application effect is unstable. However, the strain is not the only reason that affects the effect of fertilizers. In fact, the mutual ratio between microbial strains and other components in fertilizers will also affect the effect of fertilizers. In the preparation process of existing composite microbial fertilizers, microorganisms and fertilizers are directly mixed and granulated. High temperature, dryness and other factors will cause a large number of microorganisms to die. Inorganic fertilizers, especially high nitrogen, have a strong killing power on microorganisms and affect the activity of microorganisms. In order to improve the effective activity of functional microorganisms in microbial compound fertilizers during storage, it is crucial to study the effects of different microbial coating materials on the number of live bacteria. Summary of the invention

[0004] In view of the above problems, the present invention provides a microbial composite fertilizer and a preparation method and application thereof. The composite microorganisms are loaded by a carbon-based porous carrier and a modified sepiolite respectively to improve the loading rate of the composite microorganisms. Then, the carbon-based porous carrier and the modified sepiolite are cross-linked to coat the composite microorganisms. After the hydrogel coats them, the hydrogel can absorb and retain a large amount of water and solute molecules in a swollen state, so that it not only has the dual effects of water retention and fertilizer slow release, but also improves the utilization rate of fertilizer, while promoting the activity of the composite microorganisms, increasing the utilization rate of the composite microorganisms, thereby improving the soil structure, increasing the porosity, and improving the functional diversity of soil microorganisms.

[0005] The first object of the present invention is to provide a microbial composite fertilizer, wherein the microbial composite fertilizer is a wall material of a mixture of hydrogel and fertilizer, a composite porous carrier is used to load the composite microorganisms and then cross-linked and coated to form a core material, and the core material is coated by the wall material; the core material is a carbon-based porous carrier and a modified sepiolite, both of which are loaded with composite microorganisms and then cross-linked to form a porous carrier, and the carbon-based porous carrier is formed by modifying a mixture of sawdust and coconut husk through a hydrothermal reaction.

[0006] A second object of the present invention is to provide a method for preparing the above-mentioned microbial compound fertilizer, comprising the following steps:

[0007] S1. Soak the carbon-based porous carrier and the modified sepiolite in the composite microbial fermentation liquid for loading, then mix and heat to 30-35° C. for reaction, and filter and dry to constant weight to form a core material;

[0008] S2. Add sodium lignin sulfonate solution to the core material obtained in S1, stir evenly, then add calcium alginate solution and fertilizer, stir evenly, solidify to form hydrogel wall material to coat the core material, and then filter and dry to form microbial compound fertilizer.

[0009] Preferably, in S1, the method for preparing the carbon-based porous carrier comprises the following steps:

[0010] The sawdust and coconut chaff are crushed and mixed, and then soaked in a potassium hydroxide solution for 48 to 72 hours. After the soaking, they are transferred to a reactor for hydrothermal reaction. After the reaction, they are washed to neutrality and then freeze-dried to obtain a carbon-based porous carrier.

[0011] Preferably, the mass ratio of the sawdust to the coconut chaff is 5:2-3, the solid-liquid ratio of the mixture to the potassium hydroxide solution is 1 g:15 mL, the concentration of the potassium hydroxide solution is 3-5 mol / L, the temperature of the hydrothermal reaction is 180-240° C., the time is 2-3 h, and the freeze-drying temperature is -30--20° C., and the time is 8-10 h.

[0012] Preferably, in S1, the method for preparing the composite microbial fermentation broth comprises the following steps:

[0013] Inoculating Bacillus subtilis seed liquid, Bacillus laterosporus seed liquid and Bacillus colloids seed liquid into liquid culture medium for fermentation to form Bacillus subtilis fermentation liquid, Bacillus laterosporus fermentation liquid and Bacillus colloids fermentation liquid respectively, mixing them evenly and then adding functional bacterial agent;

[0014] The inoculation amount of Bacillus subtilis seed solution, Bacillus laterosporus seed solution and Bacillus colloids seed solution is 8-10 mL seed solution / kg substrate; the number of effective live bacteria in the Bacillus subtilis fermentation liquid, Bacillus laterosporus fermentation liquid and Bacillus colloids fermentation liquid is ≥5×10 10 cfu / g.

[0015] Preferably, the addition amount of the functional bacterial agent is 8% of the total mass of the composite Bacillus fermentation broth, and the functional bacterial agent is a mixture of nitrogen-fixing bacteria, rhizobia and phosphate-solubilizing bacteria in a mass ratio of 2:1:2, and the number of effective live bacteria in the nitrogen-fixing bacteria, rhizobia and phosphate-solubilizing bacteria is ≥2×10 10 cfu / g.

[0016] Preferably, in S1, the mass ratio of the carbon-based porous carrier to the composite microbial fermentation broth is 1:3, the mass ratio of the modified sepiolite to the composite microbial fermentation broth is 1:2, the soaking time is 8 to 12 hours, and the drying temperature is 30°C.

[0017] Preferably, in S2, the mass ratio of the sodium lignin sulfonate solution to the core material is 4:1, the concentration of the sodium lignin sulfonate solution is 15%, the concentration of the calcium alginate solution is 3%, and the mass ratio of the calcium alginate solution to the sodium lignin sulfonate solution is 1:4.

[0018] Preferably, in S2, the fertilizers are potassium dihydrogen phosphate and urea, the mass ratio of potassium dihydrogen phosphate to urea is 2:1, the amount of fertilizer added is 5% of the total amount of hydrogel, the reaction temperature is 30°C, the time is 2 to 4 hours, the drying temperature is 30°C, and the moisture content of the microbial compound fertilizer obtained after drying is 5 to 8%.

[0019] The third object of the present invention is to provide the application of the above-mentioned microbial compound fertilizer in the growth of crops.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The present invention loads the composite microorganisms by using a carbon-based porous carrier and a modified sepiolite respectively to increase the loading rate of the composite microorganisms. Then, the carbon-based porous carrier and the modified sepiolite are cross-linked to coat the composite microorganisms, and then a hydrogel is used to coat the carbon-based porous carrier and the modified sepiolite cross-linked product for a second time. The hydrogel can absorb and retain a large amount of water and solute molecules in a swollen state, thereby promoting the activity of the composite microorganisms and increasing the storage stability of the composite microorganisms. At the same time, the hydrogel is also coated with fertilizer, so that it not only has the dual effects of water retention and fertilizer slow release, but also improves the utilization rate of fertilizer, provides organic carbon and the content of nutrients such as nitrogen, phosphorus, and potassium for strawberries, and at the same time promotes the utilization rate of the composite microorganisms, thereby improving the soil structure, increasing the porosity, and improving the functional diversity of soil microorganisms.

[0022] (2) The present invention prepares a carbon-based porous carrier through a hydrothermal method, which increases the void structure and porosity of the carbon-based materials sawdust and coconut bran, increases the close binding with microorganisms, and the carbon-based materials and modified sepiolite provide organic matter and a habitat for the survival and growth of microorganisms, thereby improving the nutrient conversion rate and the number of beneficial microorganisms in the product, promoting soil remediation, improving soil fertility, enhancing the disease resistance of crops, and improving crop quality; after the hydrogel is mixed with the carbon-based material and modified sepiolite, the stability of the hydrogel can be increased, and it is easy to degrade in the natural environment, is environmentally friendly, and improves the soil porosity and permeability to improve the physical structure of the soil, effectively alleviating the drought effect on crops. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention is a process flow chart for preparing microbial compound fertilizer. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] It should be noted that the professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specifically stated, the various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0026] The Bacillus subtilis seed solution, the Bacillus laterosporus seed solution, and the Bacillus mucilaginosus seed solution in the examples were all cultured by conventional methods, and the nitrogen-fixing bacteria agent, the rhizobium agent, and the phosphate-solubilizing bacteria agent used were purchased from Paul Timhan (Weifang) Biotechnology Co., Ltd., and the test methods described in the following examples, unless otherwise specified, are all conventional methods.

[0027] The method for modifying sepiolite adopts a conventional acid activation modification method, including the following steps: adding a 10% HCl solution to the sepiolite ore, the solid-liquid ratio of the sepiolite ore and the HCl solution is 1:10, constant temperature water bath at 80°C for 8 hours, washing and filtering multiple times to remove the acid until the sepiolite becomes neutral, drying and grinding the neutral sepiolite, and obtaining acid-activated modified sepiolite.

[0028] Example 1

[0029] A microbial composite fertilizer, wherein the wall material is a mixture of hydrogel and fertilizer, the composite microorganisms are loaded on a composite porous carrier and then cross-linked and coated to form a core material, and the core material is coated by the wall material; the core material is a carbon-based porous carrier and a modified sepiolite, both of which are loaded with composite microorganisms and then cross-linked to form the core material, and the carbon-based porous carrier is formed by modifying a mixture of sawdust and coconut chaff through a hydrothermal reaction.

[0030] The preparation method of the above-mentioned microbial compound fertilizer is as follows: Figure 1 As shown, the following steps are included:

[0031] S1. Preparation of composite microbial fermentation liquid:

[0032] Bacillus subtilis seed liquid, Bacillus laterosporus seed liquid and Bacillus colloids seed liquid were inoculated in liquid culture medium respectively, with the inoculation amount of 10 mL seed liquid / kg substrate, cultured at 200 r / min and 37° C. for 48 h, fermented to form Bacillus subtilis fermentation liquid, Bacillus laterosporus fermentation liquid and Bacillus colloids fermentation liquid, mixed evenly and then added with functional bacterial agent, the addition amount of functional bacterial agent was 8% of the total mass of composite Bacillus fermentation liquid;

[0033] The liquid culture medium is 0.5% glucose, 3% starch, 3% soybean meal, 1.0% corn steep liquor, 0.5% yeast powder, 0.2% disodium hydrogen phosphate, 0.1% magnesium sulfate, 0.01% manganese sulfate, 2u / g starch of common α-amylase, and 10u / g soybean meal of protease addition;

[0034] The effective viable bacteria count in the Bacillus subtilis fermentation liquid, the Bacillus laterosporus fermentation liquid and the Bacillus mucilaginosus fermentation liquid is ≥5×10 10 cfu / g;

[0035] The functional bacterial agent is a mixture of nitrogen-fixing bacteria, rhizobia and phosphate-solubilizing bacteria in a mass ratio of 2:1:2, and the number of effective live bacteria in the nitrogen-fixing bacteria, rhizobia and phosphate-solubilizing bacteria is ≥2×10 10 cfu / g;

[0036] Preparation of carbon-based porous support:

[0037] Sawdust and coconut bran were crushed and mixed in a mass ratio of 5:3, and then soaked in a 5 mol / L potassium hydroxide solution for 72 hours, with a solid-liquid ratio of the mixture to the potassium hydroxide solution of 1 g:15 mL. After the soaking, the mixture was transferred to a reactor for hydrothermal reaction at 200°C for 3 hours. After the reaction, the mixture was washed with water until neutral and then freeze-dried at -20°C for 10 hours to obtain a carbon-based porous carrier.

[0038] Preparation of core material:

[0039] The carbon-based porous carrier and the modified sepiolite were respectively immersed in the composite microbial fermentation liquid for loading for 10 hours, wherein the mass ratio of the carbon-based porous carrier to the composite microbial fermentation liquid was 1:3, and the mass ratio of the modified sepiolite to the composite microbial fermentation liquid was 1:2, and then the two were mixed and heated to 30-35°C for reaction for 4 hours, and filtered and dried to constant weight to form a core material;

[0040] S2. Add a 15% sodium lignin sulfonate solution to the core material obtained in S1, the mass ratio of the sodium lignin sulfonate solution to the core material is 4:1, and after stirring evenly at 30°C, add a 3% calcium alginate solution and fertilizer and stir evenly, the mass ratio of the calcium alginate solution to the sodium lignin sulfonate solution is 1:4, the fertilizer is potassium dihydrogen phosphate and urea, the mass ratio of potassium dihydrogen phosphate to urea is 2:1, and the amount of fertilizer added is 5% of the total amount of the hydrogel. After reacting for 3 hours, solidify to form a hydrogel wall material to coat the core material, and then filter and dry to form a microbial compound fertilizer. The moisture content of the microbial compound fertilizer obtained after drying is 8%.

[0041] Example 2

[0042] A microbial composite fertilizer, wherein the wall material is a mixture of hydrogel and fertilizer, the composite microorganisms are loaded on a composite porous carrier and then cross-linked and coated to form a core material, and the core material is coated by the wall material; the core material is a carbon-based porous carrier and a modified sepiolite, both of which are loaded with composite microorganisms and then cross-linked to form the core material, and the carbon-based porous carrier is formed by modifying a mixture of sawdust and coconut chaff through a hydrothermal reaction.

[0043] The preparation method of the above-mentioned microbial compound fertilizer comprises the following steps:

[0044] S1. Method for preparing composite microbial fermentation liquid:

[0045] Bacillus subtilis seed liquid, Bacillus laterosporus seed liquid and Bacillus colloids seed liquid were inoculated in liquid culture medium respectively, with the inoculation amount of 8 mL seed liquid / kg substrate, cultured at 200 r / min and 37° C. for 48 h, fermented to form Bacillus subtilis fermentation liquid, Bacillus laterosporus fermentation liquid and Bacillus colloids fermentation liquid, mixed evenly and then added with functional bacterial agent, the addition amount of functional bacterial agent was 8% of the total mass of composite Bacillus fermentation liquid;

[0046] The liquid culture medium is 0.5% glucose, 3% starch, 3% soybean meal, 1.0% corn steep liquor, 0.5% yeast powder, 0.2% disodium hydrogen phosphate, 0.1% magnesium sulfate, 0.01% manganese sulfate, 2u / g starch of common α-amylase, and 10u / g soybean meal of protease addition;

[0047] The effective viable bacteria count in the Bacillus subtilis fermentation liquid, the Bacillus laterosporus fermentation liquid and the Bacillus mucilaginosus fermentation liquid is ≥5×10 10 cfu / g;

[0048] The functional bacterial agent is a mixture of nitrogen-fixing bacteria, rhizobia and phosphate-solubilizing bacteria in a mass ratio of 2:1:2, and the number of effective live bacteria in the nitrogen-fixing bacteria, rhizobia and phosphate-solubilizing bacteria is ≥2×10 10 cfu / g;

[0049] Method for preparing carbon-based porous carrier:

[0050] Sawdust and coconut husk were crushed and mixed at a mass ratio of 5:2, and then soaked in a 3 mol / L potassium hydroxide solution for 60 hours, with a solid-liquid ratio of the mixture to the potassium hydroxide solution of 1 g:15 mL. After soaking, the mixture was transferred to a reactor for hydrothermal reaction at 180°C for 3 hours. After the reaction, the mixture was washed with water until neutral, and then freeze-dried at -30°C for 8 hours to obtain a carbon-based porous carrier.

[0051] The method for preparing the core material is the same as in Example 1;

[0052] S2. Add a 15% sodium lignin sulfonate solution to the core material obtained in S1, the mass ratio of the sodium lignin sulfonate solution to the core material is 4:1, and after stirring evenly at 30°C, add a 3% calcium alginate solution and fertilizer and stir evenly, the mass ratio of the calcium alginate solution to the sodium lignin sulfonate solution is 1:4, the fertilizer is potassium dihydrogen phosphate and urea, the mass ratio of potassium dihydrogen phosphate to urea is 2:1, and the amount of fertilizer added is 5% of the total amount of the hydrogel. After reacting for 4 hours, solidify to form a hydrogel wall material to coat the core material, and then filter and dry to form a microbial compound fertilizer. The moisture content of the microbial compound fertilizer obtained after drying is 5%.

[0053] Example 3

[0054] A microbial composite fertilizer, wherein the wall material is a mixture of hydrogel and fertilizer, the composite microorganisms are loaded on a composite porous carrier and then cross-linked and coated to form a core material, and the core material is coated by the wall material; the core material is a carbon-based porous carrier and a modified sepiolite, both of which are loaded with composite microorganisms and then cross-linked to form the core material, and the carbon-based porous carrier is formed by modifying a mixture of sawdust and coconut chaff through a hydrothermal reaction.

[0055] The preparation method of the above-mentioned microbial compound fertilizer comprises the following steps:

[0056] S1. Method for preparing composite microbial fermentation liquid:

[0057] Bacillus subtilis seed liquid, Bacillus laterosporus seed liquid and Bacillus colloids seed liquid were inoculated in liquid culture medium respectively, with the inoculation amount of 10 mL seed liquid / kg substrate, cultured at 200 r / min and 37° C. for 48 h, fermented to form Bacillus subtilis fermentation liquid, Bacillus laterosporus fermentation liquid and Bacillus colloids fermentation liquid, mixed evenly and then added with functional bacterial agent, the addition amount of functional bacterial agent was 8% of the total mass of composite Bacillus fermentation liquid;

[0058] The liquid culture medium is the same as in Example 1;

[0059] Method for preparing carbon-based porous carrier:

[0060] Sawdust and coconut husk were crushed and mixed at a mass ratio of 5:2, and then soaked in a 4 mol / L potassium hydroxide solution for 48 hours, with a solid-liquid ratio of the mixture to the potassium hydroxide solution of 1 g:15 mL. After soaking, the mixture was transferred to a reactor for hydrothermal reaction at 240°C for 2 hours. After the reaction, the mixture was washed with water until neutral, and then freeze-dried at -25°C for 8 hours to obtain a carbon-based porous carrier.

[0061] The method for preparing the core material is the same as in Example 1;

[0062] S2. Add a 15% sodium lignin sulfonate solution to the core material obtained in S1, the mass ratio of the sodium lignin sulfonate solution to the core material is 4:1, and after stirring evenly at 30°C, add a 3% calcium alginate solution and fertilizer and stir evenly, the mass ratio of the calcium alginate solution to the sodium lignin sulfonate solution is 1:4, the fertilizer is potassium dihydrogen phosphate and urea, the mass ratio of potassium dihydrogen phosphate to urea is 2:1, and the amount of fertilizer added is 5% of the total amount of the hydrogel. After reacting for 4 hours, solidify to form a hydrogel wall material to coat the core material, and then filter and dry to form a microbial compound fertilizer. The moisture content of the microbial compound fertilizer obtained after drying is 5%.

[0063] Comparative Example 1

[0064] A method for preparing a microbial compound fertilizer is basically the same as that in Example 1, except that the core material in S1 only uses a carbon-based porous carrier to load microbial fermentation bacteria.

[0065] Comparative Example 2

[0066] A method for preparing a microbial compound fertilizer is basically the same as that in Example 1, except that the core material in S1 only uses modified sepiolite loaded with microbial fermentation bacteria.

[0067] Comparative Example 3

[0068] A method for preparing a microbial compound fertilizer is basically the same as that in Example 1, except that in S1, after the sawdust and coconut chaff are crushed and mixed, they are not modified and are directly immersed in a composite microbial fermentation liquid for loading.

[0069] Comparative Example 4

[0070] A method for preparing a microbial compound fertilizer is basically the same as that in Example 1, except that in S1, a carbon-based porous carrier and a modified sepiolite are compositely immersed in a composite microbial fermentation broth for loading, and a mass ratio of the carbon-based porous carrier, the modified sepiolite and the composite microbial fermentation broth is 1:1:5.

[0071] Comparative Example 5

[0072] A method for preparing a microbial compound fertilizer, wherein only a core material is prepared to form the microbial compound fertilizer, and the preparation of the core material is the same as in Example 1.

[0073] The number of effective live bacteria in the core materials of the microbial compound fertilizers prepared in Example 1 and Comparative Examples 1 to 3 was detected respectively. 50 g of the core materials prepared in Example 1 and Comparative Examples 1-3 were weighed and placed in 0.9% saline until they were completely dissolved. The filtrate was filtered to obtain the filtrate, and then counted with a hemocytometer, as shown in Table 1.

[0074] Table 1 Effective number of live bacteria in the core material of microbial compound fertilizer

[0075] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 <![CDATA[Number of viable bacteria (10 10 CFU / ml)]]> 17.8 7.3 5.5 8.4 10.5

[0076] It can be seen from Table 1 that the effective live bacteria count of microorganisms in the core material prepared in Example 1 is greater than that in Comparative Examples 1 to 4. This is because the present invention loads the composite microorganisms on the carbon-based porous carrier and the modified sepiolite respectively, and then cross-links the hydrophilic groups on the carbon-based porous carrier and the hydrophilic groups on the modified sepiolite to coat the composite microorganisms, thereby increasing the loading rate of the composite microorganisms. When the carbon-based porous carrier and the modified sepiolite are immersed and loaded at the same time, the carbon-based porous carrier and the modified sepiolite are cross-linked in the process of loading the microorganisms, thereby reducing the loading rate of the composite microorganisms.

[0077] After the microbial compound fertilizers prepared in Example 1 and Comparative Examples 1 to 5 were stored at room temperature for 90 days, the number of effective live bacteria in the microbial compound fertilizers was detected. The specific results are shown in Table 2.

[0078] Table 2 Effective number of live bacteria after storage of microbial compound fertilizer for 90 days

[0079]

[0080] As can be seen from Table 2, after 90 days of storage at room temperature, the effective viable bacterial survival rate of the composite microorganisms in Example 1 can still reach more than 90%, while the composite microorganisms without hydrogel coating, such as Comparative Example 5, have an effective viable bacterial survival rate of about 50%. It can be seen that after being coated with the carbon-based porous carrier and the modified sepiolite, and then coated with the hydrogel for the second time, the water and solute molecules absorbed and retained in the hydrogel are in a swollen state, which promotes the activity of the composite microorganisms and improves the composite microorganisms. The survival rate of the composite microorganisms is improved, thereby making the composite microorganisms have good room temperature storage properties; while in Comparative Example 1, the hydrophilic groups of the carbon-based porous carrier are cross-linked and coated with the hydrophilic groups of the hydrogel, and the effective live bacteria survival rate of the modified sepiolite and the cross-linked and coated hydrogel in Comparative Example 2 and Comparative Example 3 is about 80%, while in Comparative Example 4, the carbon-based porous carrier and the modified sepiolite are cross-linked in the process of loading microorganisms, and the composite microorganisms loaded by the carbon-based porous carrier and the modified sepiolite are less coated, thereby reducing the survival rate of the composite microorganisms.

[0081] The effect of the present invention is further described below in conjunction with the application of the microbial composite agent prepared by the present invention in the cultivation of pakchoi. The specific test process and results are as follows.

[0082] Test subjects: 4 treatment groups and 1 control group were set up, and 1 mu of test field was selected in the pakchoi planting base and divided into 5 groups, wherein the 4 treatment groups were respectively applied with the microbial composite agent prepared in Example 1 and the microbial composite agent prepared in Comparative Examples 3-5, and the last group was a blank control group, without adding any microbial composite agent; the 5 groups of test fields were all applied with ordinary farmyard manure before planting pakchoi, and the application amount of farmyard manure was 400 kg / mu; while applying farmyard manure, the 4 treatment groups were respectively applied with the microbial composite agent prepared in Example 1 and the microbial composite agent prepared in Comparative Examples 3-5, and the application amount was 20 kg / mu.

[0083] The pakchoy was sown on September 5, 2022. The pakchoy was watered regularly and quantitatively on a daily basis. No compound fertilizer or insecticide was applied to the pakchoy during its growth. The pakchoy was harvested on October 10, and soil was collected on the same day to measure the physical and chemical properties of the soil and the physiological and biochemical indicators of the pakchoy. The specific results are shown in Tables 3 and 4.

[0084] Table 3 Soil physical and chemical properties test results

[0085]

[0086] As can be seen from Table 3, after applying the microbial compound fertilizer of Example 1 to the soil of the pakchoi test field, the soil microenvironment can be improved, and the microbial compound bacteria in the microbial compound fertilizer can increase the content of nitrogen, phosphorus and potassium in the soil, thereby improving soil fertility and meeting the needs of soil microorganisms and crop growth. The physical and chemical properties of the soil are greatly improved compared with comparative examples 3 to 4 and the control group, the content of nutrient elements in the soil is greatly increased, the fertility is also greatly improved, and the soil bulk density is reduced, the soil porosity is increased, and the physical and chemical properties of the soil are better.

[0087] The number of microorganisms in Comparative Examples 3 and 4 is relatively small, so the soil effects in all aspects are worse than those in Example 1, but the differences are not significant; Comparative Example 5 lacks the coordination effect of the hydrogel, so its effect is not as good as that in Example 1, nor as good as that in Comparative Examples 3 to 4.

[0088] Table 4 Physiological and biochemical indicators of Chinese cabbage

[0089]

[0090]

[0091] It can be seen from Table 4 that after the microbial composite agent of Example 1 was applied to plant Chinese cabbage, the incidence rate of Chinese cabbage was reduced to 6.1%, the chlorophyll and vitamin C contents were increased by 2 times, and the yield was increased by 25.3% compared with the Chinese cabbage planted without the microbial composite agent. It can be seen that the microbial composite agent of the present invention can improve the physical and chemical properties of the soil. At the same time, the hydrogel not only has the dual effects of water retention and fertilizer slow release, but also improves the utilization rate of fertilizer, while promoting the activity of the composite microorganisms, increasing the utilization rate of the composite microorganisms, thereby improving the soil structure, increasing the porosity, and improving the functional diversity of soil microorganisms, thereby increasing crop yields.

[0092] Since the number of microorganisms in Comparative Examples 3 to 5 is relatively small, the soil effects in all aspects are worse than those in Example 1, and the yield of the cultivated Chinese cabbage is also less than that in Example 1; in Comparative Example 5, the coordination effect of the hydrogel is lacking, and the physical and chemical properties of the soil are worse, so the incidence of Chinese cabbage increases, the chlorophyll and vitamin C contents decrease, and the yield is low.

[0093] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0094] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A microbial compound fertilizer, characterized in that: The microbial composite fertilizer is formed by using a mixture of hydrogel and fertilizer as the wall material, and the composite microorganisms are loaded with a composite porous carrier and then cross-linked and coated to form a core material, and the core material is coated with the wall material; The preparation method of modified sepiolite comprises the following steps: Adding a 10% HCl solution to the sepiolite ore, the solid-liquid ratio of the sepiolite ore to the HCl solution is 1:10, keeping it in a constant temperature water bath at 80°C for 8 hours, washing and filtering multiple times to remove the acid solution until the sepiolite becomes neutral, drying and grinding the neutral sepiolite to obtain acid-activated modified sepiolite; The preparation method of microbial compound fertilizer comprises the following steps: S1. Soak the carbon-based porous carrier and the modified sepiolite in the composite microbial fermentation liquid for loading, then mix and heat to 30-35°C for reaction, and filter and dry to constant weight to form a core material; S2, adding sodium lignin sulfonate solution to the core material obtained in S1, stirring evenly, then adding calcium alginate solution and fertilizer, stirring evenly, solidifying to form a hydrogel wall material to coat the core material, and then filtering and drying to form a microbial compound fertilizer; The method for preparing the carbon-based porous carrier comprises the following steps: The sawdust and coconut husk are crushed and mixed, and then soaked in a potassium hydroxide solution for 48 to 72 hours. After the soaking, they are transferred to a reactor for hydrothermal reaction. After the reaction, they are washed to neutrality and freeze-dried to obtain a carbon-based porous carrier. The mass ratio of the carbon-based porous carrier to the composite microbial fermentation broth is 1:3, and the mass ratio of the modified sepiolite to the composite microbial fermentation broth is 1:

2.

2. The microbial compound fertilizer according to claim 1, characterized in that: The mass ratio of sawdust to coconut chaff is 5:2-3, the solid-liquid ratio of the mixture to the potassium hydroxide solution is 1 g:15 mL, the concentration of the potassium hydroxide solution is 3-5 mol / L, the temperature of the hydrothermal reaction is 180-240° C., the time is 2-3 h, and the temperature of the freeze-drying is -30--20° C., and the time is 8-10 h.

3. The microbial compound fertilizer according to claim 1, characterized in that: In S1, the method for preparing the composite microbial fermentation broth comprises the following steps: Inoculating Bacillus subtilis seed liquid, Bacillus laterosporus seed liquid and Bacillus colloids seed liquid into liquid culture medium for fermentation to form Bacillus subtilis fermentation liquid, Bacillus laterosporus fermentation liquid and Bacillus colloids fermentation liquid respectively, mixing them evenly and then adding functional bacterial agent; The inoculation amount of Bacillus subtilis seed solution, Bacillus laterosporus seed solution and Bacillus colloids seed solution is 8-10 mL seed solution / kg matrix; the number of effective live bacteria in the Bacillus subtilis fermentation liquid, Bacillus laterosporus fermentation liquid and Bacillus colloids fermentation liquid is ≥5×10 10 cfu / g.

4. The microbial compound fertilizer according to claim 3, characterized in that: The addition amount of the functional bacterial agent is 8% of the total mass of the composite Bacillus fermentation liquid. The functional bacterial agent is a mixture of nitrogen-fixing bacteria, rhizobia and phosphate-solubilizing bacteria in a mass ratio of 2:1:

2. The number of effective live bacteria in the nitrogen-fixing bacteria, rhizobia and phosphate-solubilizing bacteria is ≥2×10 10 cfu / g.

5. The microbial compound fertilizer according to claim 1, characterized in that: In S1, the soaking time is 8-12 h and the drying temperature is 30 °C.

6. The microbial compound fertilizer according to claim 1, characterized in that: In S2, the mass ratio of the sodium lignin sulfonate solution to the core material is 4:1, the concentration of the sodium lignin sulfonate solution is 15%, the concentration of the calcium alginate solution is 3%, and the mass ratio of the calcium alginate solution to the sodium lignin sulfonate solution is 1:

4.

7. The microbial compound fertilizer according to claim 1, characterized in that: In S2, the fertilizers are potassium dihydrogen phosphate and urea, the mass ratio of potassium dihydrogen phosphate to urea is 2:1, the amount of fertilizer added is 5% of the total amount of hydrogel, the reaction temperature is 30°C, the time is 2~4h, the drying temperature is 30°C, and the moisture content of the microbial compound fertilizer obtained after drying is 5~8%.

8. Use of the microbial compound fertilizer according to claim 1 in the growth of crops.

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