Environment-friendly organic fertilizer and preparation method thereof

Abstract

The invention discloses an environment-friendly organic fertilizer and a preparation method thereof, and belongs to the technical field of organic fertilizers. Corn straws and cottonseed cakes are crushed and mixed to obtain an agricultural waste mixture; after the bacillus subtilis is activated for three generations, thalli are collected and freeze-dried to obtain bacillus subtilis powder; activating lactic acid bacteria for three generations, collecting thalli, and freeze-drying to obtain lactic acid bacteria powder; the bacillus subtilis powder and the lactic acid bacteria powder are mixed to obtain a compound microbial agent; mixing the agricultural waste mixture, the compound microbial agent, the functional biochar and the oyster shell powder to obtain a mixed material; sequentially fermenting and drying the mixed material to obtain the environment-friendly organic fertilizer. According to the invention, a phosphorylated bamboo charcoal-chitosan / sodium alginate composite carrier is constructed, nitrogen-fixing bacteria are loaded, and the nitrogen-fixing bacteria and the composite microbial inoculant have a synergistic effect, so that microbial activity and a material structure are optimized in fermentation, and the problem that microbial activity maintenance, nutrient efficiency and environmental safety of a traditional organic fertilizer are difficult to consider at the same time is solved.

Description

Technical Field

[0001] This invention relates to the field of organic fertilizer technology, specifically to an environmentally friendly organic fertilizer and its preparation method. Background Technology

[0002] Traditional organic fertilizers largely rely on livestock and poultry manure composting, which suffers from high heavy metal residues, long fermentation cycles, and significant greenhouse gas emissions. Current technologies often utilize agricultural waste such as straw through simple mixed fermentation, but this is inefficient and prone to ammonia volatilization, resulting in high nitrogen loss rates. Some improved solutions add single microorganisms or biochar, but these do not address the synergistic problem of insufficient microbial activity and high environmental risk, failing to simultaneously achieve high fertilizer efficiency and environmental friendliness.

[0003] Patent CN108947600A discloses a method for preparing organic fertilizer, relating to the field of organic fertilizer production technology. This method produces organic fertilizer by composting organic waste materials mixed with microbial agents (including Bacillus licheniformis, Bacillus subtilis, Pediococcus pentosaceus, and Trichoderma). The aforementioned microbial agents can effectively decompose organic waste materials through the synergistic effect between strains, improving the quality of organic fertilizer and facilitating crop absorption. However, while this method improves the utilization rate of organic waste to some extent, its nitrogen fixation capacity during fermentation is weak, leading to nutrient loss due to ammonia volatilization, and it fails to adequately consider soil improvement and water retention capacity enhancement.

[0004] Patent CN113461456A discloses an organic fertilizer and its preparation method, which includes pulverizing a fermentation substrate, inoculating it with fermentation bacteria for pre-fermentation, and then mixing it evenly with a fertilizer synergist through subsequent composting fermentation, followed by drying and granulation. The organic fertilizer prepared by this method can reduce nutrient loss and improve the fertilizer's water retention, thereby enhancing its effectiveness. However, the specific mechanism of action of the fertilizer synergist in this technical solution is not clearly explained, which may lead to unstable effects in practical applications; in addition, its preparation process requires sophisticated equipment, increasing production costs and limiting its scope of application.

[0005] Therefore, there is an urgent need for an organic fertilizer solution that can balance waste treatment, microbial activity regulation, and environmental safety. Summary of the Invention

[0006] This invention constructs a multifunctional microbial carrier by phosphorylating and modifying bamboo-based biochar and encapsulating it with chitosan-sodium alginate hydrogel. This carrier not only effectively loads and protects nitrogen-fixing bacteria, but also optimizes material structure and regulates microbial activity during fermentation through synergistic effects with Bacillus subtilis and lactic acid bacteria. The final product achieves efficient conversion of agricultural waste, provides balanced nutrients, and immobilizes heavy metals, solving the problem of traditional organic fertilizers that struggle to balance microbial activity maintenance, nutrient efficiency, and environmental safety. Specifically, the technical solution of this invention includes the following: A method for preparing an environmentally friendly organic fertilizer, the method comprising the following steps: A mixture of crushed corn stalks and cottonseed cake is obtained by mixing them to produce an agricultural waste mixture. After Bacillus subtilis is activated for three generations, the bacterial cells are collected and freeze-dried to obtain Bacillus subtilis powder. Lactic acid bacteria were activated for three generations, and the bacterial cells were collected and freeze-dried to obtain lactic acid bacteria powder. A compound microbial agent is obtained by mixing Bacillus subtilis powder and lactic acid bacteria powder; A mixture of agricultural waste, compound microbial inoculants, functionalized biochar, and oyster shell powder is prepared. The mixture is fermented and dried in sequence to produce environmentally friendly organic fertilizer.

[0007] Furthermore, the corn stalks and cottonseed cake are crushed and mixed at a weight ratio of 2~4:1~2.5.

[0008] Furthermore, the activation of Bacillus subtilis involves inoculating Bacillus subtilis into LB liquid medium and culturing it at 30°C with shaking at 150 r / min for 24 h to complete one generation of activation. Repeating the above operation three times constitutes three generations of activation.

[0009] Furthermore, the activation of lactic acid bacteria involves inoculating lactic acid bacteria into MRS medium and incubating them at 37°C for 48 hours to complete one generation of activation. Repeating this process three times completes three generations of activation.

[0010] Furthermore, the weight ratio of Bacillus subtilis powder to lactic acid bacteria powder is 2.5~3.5:1.

[0011] Furthermore, the preparation method of the functionalized biochar includes the following steps: Bamboo is crushed and kept at 500℃ for 6 hours to obtain raw bamboo charcoal. Phosphorylated biochar was obtained by mixing and stirring raw bamboo char with 15 wt% phosphoric acid solution. Chitosan and 1 wt% acetic acid solution are mixed to obtain chitosan acetate solution, sodium alginate and deionized water are mixed to obtain sodium alginate aqueous solution, and chitosan acetate solution and sodium alginate aqueous solution are mixed to obtain coating solution; Phosphorylated biochar and coating solution were mixed and stirred, and then freeze-dried to obtain composite biochar. Functionalized biochar was prepared by mixing a suspension of Vignelandia diffusa and composite biochar, allowing it to stand, and then collecting the solid.

[0012] Furthermore, the weight ratio of the raw bamboo charcoal to the 15wt% phosphoric acid solution is 10:80~100.

[0013] Furthermore, the conditions for the stirring reaction of the raw bamboo charcoal and 15wt% phosphoric acid solution include a reaction temperature of 25°C and a reaction time of 20~24h.

[0014] Furthermore, the weight ratio of chitosan to 1 wt% acetic acid solution is 1.5~2:100.

[0015] Furthermore, the weight ratio of sodium alginate to deionized water is 1.5~2:100.

[0016] Furthermore, the weight ratio of the phosphorylated biochar to the coating solution is 10:80~100.

[0017] Furthermore, the mixing conditions for the phosphorylated biochar and the coating solution include a mixing temperature of 25°C and a mixing time of 30-60 min.

[0018] Furthermore, the freeze-drying conditions include pre-freezing at -80°C for 2 hours, followed by freeze-drying at -50°C for 24 hours.

[0019] Furthermore, the weight ratio of the Viñelandia diffusa suspension to the composite biochar is 1~1.5:1.

[0020] Furthermore, the conditions for settling include a settling temperature of 4°C and a settling time of 12-16 hours.

[0021] Furthermore, the weight ratio of the agricultural waste mixture, compound microbial agent, functionalized biochar, and oyster shell powder is 60~70:3~5:3~5:1~2.

[0022] Furthermore, the mixing conditions for the agricultural waste mixture, compound microbial agent, functionalized biochar and oyster shell powder include a mixing speed of 25-35 r / min and a mixing time of 15-35 min.

[0023] Furthermore, the fermentation conditions include a fermentation temperature of 45-50°C, an oxygen concentration of 3%-5%, a fermentation pH of 6.5-7.0, and a fermentation time of 20-25 days.

[0024] Furthermore, the drying process includes a drying temperature of 40~45℃, a vacuum degree of ≤5kPa, and a drying time of 8~12h.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) In this invention, bamboo pyrolysis forms original bamboo charcoal with a stable aromatic skeleton and well-developed pores. The pore structure is further expanded by the etching and dehydration effect of phosphoric acid, and oxygen-containing / phosphorus functional groups are grafted onto the surface to improve the specific surface area and chemical reactivity of the biochar. Chitosan and sodium alginate form a polyelectrolyte coating layer through electrostatic cross-linking. After freeze-drying, this hydrogel network provides a stable shelter space for microorganisms. Finally, the functionalized biochar is constructed by impregnating the Viña vinifera onto the above-mentioned multifunctional carrier.

[0026] (2) In this invention, the functional components produced a synergistic effect in the organic fertilizer system. Phosphorylated biochar transformed from an inert adsorbent into an active platform, possessing both nutrient retention and heavy metal passivation capabilities. The chitosan-sodium alginate coating protects the microbial cells when dry and provides an ideal environment for microbial revival when exposed to water. The nitrogen-fixing bacteria further endowed them with the life activity of continuously replenishing nitrogen sources. In the fermentation system, the functionalized biochar, as a physical framework, improved the aeration of the material. Its surface properties can adsorb metabolites, buffer pH fluctuations, and form a highly efficient collaboration with Bacillus subtilis (responsible for decomposing macromolecular organic matter) and lactic acid bacteria (responsible for regulating the environment and inhibiting miscellaneous bacteria). The nitrogen-fixing bacteria then activated their nitrogen-fixing function in the later stages and after application to the soil, effectively compensating for nitrogen loss.

[0027] (3) The functionalized biochar in this invention successfully solves the core bottleneck of the single function of carrier materials in the prior art. It is no longer a simple material with only physical adsorption function, but a comprehensive platform that integrates "long-term survival protection of microorganisms, slow and controlled release of nutrients, and in-situ passivation of heavy metals", which can effectively solve the problem that traditional organic fertilizers cannot simultaneously maintain microbial activity, nutrient efficiency and environmental safety. Detailed Implementation

[0028] The technical solution of the present invention will be clearly and completely described below through embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Unless otherwise stated, all raw materials and reagents used in this invention are commercially available or can be prepared by known methods.

[0030] Preparation Example 1 The preparation method of functionalized biochar includes the following steps: Bamboo is crushed to a particle size of 1 cm, placed in a tube furnace, heated to 500 °C at 5 °C / min under a nitrogen protective atmosphere, held for 6 h, and cooled to 25 °C to obtain raw bamboo charcoal. Ten parts by weight of raw bamboo charcoal were dispersed in 80 parts by weight of 15 wt% phosphoric acid aqueous solution. After stirring at 200 r / min for 20 h at 25 °C, the solid was collected by filtration and washed with deionized water until the pH of the washing solution was 6.8. The phosphorylated biochar was obtained by vacuum drying at 80 °C for 12 h. 1.5 parts by weight of chitosan (molecular weight 200kDa, degree of deacetylation 85%) were dispersed in 100 parts by weight of 1wt% acetic acid solution to obtain chitosan acetate solution, and 1.5 parts by weight of sodium alginate were dispersed in 100 parts by weight of deionized water to obtain sodium alginate aqueous solution. The chitosan acetate solution and sodium alginate aqueous solution were mixed and stirred at 300 r / min for 30 min to obtain coating solution. Ten parts by weight of phosphorylated biochar were dispersed in 80 parts by weight of coating solution and stirred at 200 r / min for 30 min at 25 °C to obtain a suspension system. The suspension system was pre-frozen at -80 °C for 2 h and then freeze-dried at -50 °C for 24 h to obtain composite biochar. *Venelandia diffusa* was inoculated into LB liquid medium and cultured at 30°C with shaking at 150 rpm until OD600 = 0.8. The cells were then collected by centrifugation at 8000 rpm for 10 min and resuspended in 0.85% sterile physiological saline, adjusting the bacterial suspension concentration to 2 × 10⁻⁶. 8 10 parts by weight of composite biochar were dispersed in 10 parts by weight of Vignalandia diffusa suspension and impregnated. The mixture was allowed to stand at 4°C for 12 h, and the solid was collected by centrifugation at 5000 r / min for 15 min. The solid was then air-dried in a sterile environment for 30 min to obtain functionalized biochar.

[0031] Preparation Example 2 The preparation method of functionalized biochar includes the following steps: Bamboo is crushed to a particle size of 2cm, placed in a tube furnace, heated to 500℃ at 5℃ / min in a nitrogen protective atmosphere, held for 6 hours, and cooled to 25℃ to obtain raw bamboo charcoal. Ten parts by weight of raw bamboo charcoal were dispersed in 85 parts by weight of 15 wt% phosphoric acid aqueous solution. After stirring at 200 r / min for 21 h at 25 °C, the solid was collected by filtration and washed with deionized water until the pH of the washing solution was 6.9. The phosphorylated biochar was obtained by vacuum drying at 80 °C for 12 h. 1.6 parts by weight of chitosan (molecular weight 200kDa, degree of deacetylation 85%) were dispersed in 100 parts by weight of 1wt% acetic acid solution to obtain chitosan acetate solution, and 1.6 parts by weight of sodium alginate were dispersed in 100 parts by weight of deionized water to obtain sodium alginate aqueous solution. The chitosan acetate solution and sodium alginate aqueous solution were mixed and stirred at 300 r / min for 30 min to obtain coating solution. Ten parts by weight of phosphorylated biochar were dispersed in 85 parts by weight of coating solution and stirred at 200 r / min for 35 min at 25 °C to obtain a suspension system. The suspension system was pre-frozen at -80 °C for 2 h and then freeze-dried at -50 °C for 24 h to obtain composite biochar. *Venelandia diffusa* was inoculated into LB liquid medium and cultured at 30°C with shaking at 150 rpm until OD600 = 0.8. The cells were then collected by centrifugation at 8000 rpm for 10 min and resuspended in 0.85% sterile physiological saline, adjusting the bacterial suspension concentration to 2 × 10⁻⁶. 8 10 parts by weight of composite biochar were dispersed in 11 parts by weight of Vignalandia diffusa suspension and impregnated. The mixture was allowed to stand at 4°C for 13 h, and the solid was collected by centrifugation at 5000 r / min for 15 min. The solid was then air-dried in a sterile environment for 35 min to obtain functionalized biochar.

[0032] Preparation Example 3 The preparation method of functionalized biochar includes the following steps: Bamboo is crushed to a particle size of 1.5 cm, placed in a tube furnace, heated to 500 °C at 5 °C / min under a nitrogen protective atmosphere, held for 6 hours, and then cooled to 25 °C to obtain raw bamboo charcoal. Ten parts by weight of raw bamboo charcoal were dispersed in 90 parts by weight of 15 wt% phosphoric acid aqueous solution. After stirring at 200 r / min for 22 h at 25 °C, the solid was collected by filtration and washed with deionized water until the pH of the washing solution was 7.0. The phosphorylated biochar was obtained by vacuum drying at 80 °C for 12 h. 1.7 parts by weight of chitosan (molecular weight 200kDa, degree of deacetylation 85%) were dispersed in 100 parts by weight of 1wt% acetic acid solution to obtain chitosan acetate solution, and 1.7 parts by weight of sodium alginate were dispersed in 100 parts by weight of deionized water to obtain sodium alginate aqueous solution. The chitosan acetate solution and sodium alginate aqueous solution were mixed and stirred at 300 r / min for 30 min to obtain coating solution. Ten parts by weight of phosphorylated biochar were dispersed in 90 parts by weight of coating solution and stirred at 200 r / min at 25℃ for 40 min to obtain a suspension system. The suspension system was pre-frozen at -80℃ for 2 h and then freeze-dried at -50℃ for 24 h to obtain composite biochar. *Venelandia diffusa* was inoculated into LB liquid medium and cultured at 30°C with shaking at 150 rpm until OD600 = 0.8. The cells were then collected by centrifugation at 8000 rpm for 10 min and resuspended in 0.85% sterile physiological saline, adjusting the bacterial suspension concentration to 2 × 10⁻⁶. 8 10 parts by weight of composite biochar were dispersed in 13 parts by weight of Vignelandia diffusa suspension and impregnated. The mixture was allowed to stand at 4°C for 14 h, and the solid was collected by centrifugation at 5000 r / min for 15 min. The solid was then air-dried in a sterile environment for 40 min to obtain functionalized biochar.

[0033] Preparation Example 4 The preparation method of functionalized biochar includes the following steps: Bamboo is crushed to a particle size of 1 cm, placed in a tube furnace, heated to 500 °C at 5 °C / min under a nitrogen protective atmosphere, held for 6 h, and cooled to 25 °C to obtain raw bamboo charcoal. Ten parts by weight of raw bamboo charcoal were dispersed in 95 parts by weight of 15 wt% phosphoric acid aqueous solution. After stirring at 200 r / min for 23 h at 25 °C, the solid was collected by filtration and washed with deionized water until the pH of the washing solution was 7.1. The phosphorylated biochar was obtained by vacuum drying at 80 °C for 12 h. 1.8 parts by weight of chitosan (molecular weight 200kDa, degree of deacetylation 85%) were dispersed in 100 parts by weight of 1wt% acetic acid solution to obtain chitosan acetate solution, and 1.8 parts by weight of sodium alginate were dispersed in 100 parts by weight of deionized water to obtain sodium alginate aqueous solution. The chitosan acetate solution and sodium alginate aqueous solution were mixed and stirred at 300 r / min for 30 min to obtain coating solution. Ten parts by weight of phosphorylated biochar were dispersed in 95 parts by weight of coating solution and stirred at 200 r / min for 50 min at 25 °C to obtain a suspension system. The suspension system was pre-frozen at -80 °C for 2 h and then freeze-dried at -50 °C for 24 h to obtain composite biochar. *Venelandia diffusa* was inoculated into LB liquid medium and cultured at 30°C with shaking at 150 rpm until OD600 = 0.8. The cells were then collected by centrifugation at 8000 rpm for 10 min and resuspended in 0.85% sterile physiological saline, adjusting the bacterial suspension concentration to 2 × 10⁻⁶. 8 10 parts by weight of composite biochar were dispersed in 14 parts by weight of Vignalandia diffusa suspension and impregnated. The mixture was allowed to stand at 4°C for 15 h, and the solid was collected by centrifugation at 5000 r / min for 15 min. The solid was then air-dried in a sterile environment for 50 min to obtain functionalized biochar.

[0034] Preparation Example 5 The preparation method of functionalized biochar includes the following steps: Bamboo is crushed to a particle size of 1 cm, placed in a tube furnace, heated to 500 °C at 5 °C / min under a nitrogen protective atmosphere, held for 6 h, and cooled to 25 °C to obtain raw bamboo charcoal. Ten parts by weight of raw bamboo charcoal were dispersed in 100 parts by weight of 15 wt% phosphoric acid aqueous solution. After stirring at 200 r / min for 24 h at 25 °C, the solid was collected by filtration and washed with deionized water until the pH of the washing solution was 7.2. The phosphorylated biochar was obtained by vacuum drying at 80 °C for 12 h. Two parts by weight of chitosan (molecular weight 200 kDa, degree of deacetylation 85%) were dispersed in 100 parts by weight of 1 wt% acetic acid solution to obtain a chitosan acetate solution. Two parts by weight of sodium alginate were dispersed in 100 parts by weight of deionized water to obtain a sodium alginate aqueous solution. The chitosan acetate solution and the sodium alginate aqueous solution were mixed and stirred at 300 r / min for 30 min to obtain a coating solution. Ten parts by weight of phosphorylated biochar were dispersed in 100 parts by weight of coating solution and stirred at 200 r / min for 60 min at 25 °C to obtain a suspension system. The suspension system was pre-frozen at -80 °C for 2 h and then freeze-dried at -50 °C for 24 h to obtain composite biochar. *Venelandia diffusa* was inoculated into LB liquid medium and cultured at 30°C with shaking at 150 rpm until OD600 = 0.8. The cells were then collected by centrifugation at 8000 rpm for 10 min and resuspended in 0.85% sterile physiological saline, adjusting the bacterial suspension concentration to 2 × 10⁻⁶. 8 10 parts by weight of composite biochar were dispersed in 15 parts by weight of Vignelandia diffusa suspension and impregnated. The mixture was allowed to stand at 4°C for 16 h, and the solid was collected by centrifugation at 5000 r / min for 15 min. The solid was then air-dried in a sterile environment for 60 min to obtain functionalized biochar.

[0035] Preparation Example 6 The preparation method of functionalized biochar includes the following steps: Replace the bamboo in Preparation Example 5 with wood chips, and keep all other operations the same as in Preparation Example 5.

[0036] Preparation Example 7 The preparation method of functionalized biochar includes the following steps: In Preparation Example 5, phosphoric acid was replaced with sulfuric acid, and all other operations were the same as in Preparation Example 5.

[0037] Preparation Example 8 The preparation method of functionalized biochar includes the following steps: Bamboo is crushed to a particle size of 1 cm, placed in a tube furnace, heated to 500 °C at 5 °C / min under a nitrogen protective atmosphere, held for 6 h, and cooled to 25 °C to obtain raw bamboo charcoal. Ten parts by weight of raw bamboo charcoal were dispersed in 100 parts by weight of 15 wt% phosphoric acid aqueous solution. After stirring at 200 r / min for 6 h at 25 °C, the mixture was placed in a muffle furnace and calcined at 220 °C for 24 h. After cooling to 25 °C, the mixture was washed with deionized water until the pH of the wash solution was 7.2. The mixture was then vacuum dried at 80 °C for 12 h to obtain phosphorylated biochar. 2.0 parts by weight of gelatin and 2.0 parts by weight of gum arabic were dispersed in 100 parts by weight of deionized water and stirred at 300 r / min for 30 min to obtain a coating solution; Ten parts by weight of phosphorylated biochar were dispersed in 100 parts by weight of coating solution and stirred at 200 r / min for 60 min at 25 °C to obtain a suspension system. The suspension system was pre-frozen at -80 °C for 2 h and then freeze-dried at -50 °C for 24 h to obtain composite biochar. *Venelandia diffusa* was inoculated into LB liquid medium and cultured at 30°C with shaking at 150 rpm until OD600 = 0.8. The cells were then collected by centrifugation at 8000 rpm for 10 min and resuspended in 0.85% sterile physiological saline, adjusting the bacterial suspension concentration to 2 × 10⁻⁶. 8 10 parts by weight of composite biochar were dispersed in 15 parts by weight of Vignelandia diffusa suspension and impregnated. The mixture was allowed to stand at 4°C for 16 h, and the solid was collected by centrifugation at 5000 r / min for 15 min. The solid was then air-dried in a sterile environment for 60 min to obtain functionalized biochar.

[0038] Preparation Example 9 The preparation method of functionalized biochar includes the following steps: The Venetian violaceae in Preparation Example 5 was replaced with rhizobia, and all other operations were the same as in Preparation Example 5.

[0039] Example 1

[0040] A method for preparing an environmentally friendly organic fertilizer includes the following steps: Corn stalks and cottonseed cake were crushed separately using a pulverizer, and the particle size was controlled by a 5mm sieve. They were then mixed at a weight ratio of 2:1 to obtain an agricultural waste mixture. Bacillus subtilis was inoculated into LB liquid medium and cultured at 30℃ with shaking at 150 r / min for 24 h to activate one generation. The above operation was repeated three times to activate three generations. After three generations, the cells were collected by centrifugation at 8000 r / min for 10 min. The cells were resuspended in sterile glycerol-skimmed milk powder protectant (glycerol 10 wt%, skimmed milk powder 15 wt%), pre-frozen at -80℃ for 2 h, and then freeze-dried at -50℃ for 24 h to obtain Bacillus subtilis powder. Lactic acid bacteria were inoculated into MRS medium and incubated statically at 37℃ for 48 hours to activate one generation. The above operation was repeated three times for three generations of activation. After three generations, the bacterial cells were collected by centrifugation at 8000 r / min for 10 min. The cells were resuspended in sterile glycerol-skimmed milk powder protectant (10 wt% glycerol, 15 wt% skimmed milk powder), pre-frozen at -80℃ for 2 hours, and then freeze-dried at -50℃ for 24 hours to obtain lactic acid bacteria powder. Bacillus subtilis powder and lactic acid bacteria powder were mixed at a weight ratio of 2.5:1 to obtain a compound microbial agent. 60 parts by weight of agricultural waste mixture, 3 parts by weight of compound microbial agent, 3 parts by weight of functionalized biochar prepared in Preparation Example 1, and 1 part by weight of oyster shell powder were placed in a mixer and stirred at a speed of 25 r / min for 15 min to obtain a mixture. The mixture was placed in a sealed fermentation tank with an initial packing density of 0.65 g / cm³. 3 The temperature was maintained at 45℃, and the headspace oxygen concentration was monitored by an oxygen sensor. When the oxygen concentration was below 3%, sterile air was introduced for 0.5 minutes to raise the oxygen concentration back to 3%, and this process was repeated every 48 hours. The pH of the material was adjusted to 6.5, and the fermentation cycle was 20 days. After fermentation, the material was transferred to a vacuum drying oven and dried for 8 hours at 40℃ and a vacuum of 5 kPa. After cooling to 25℃, the material was granulated through an 80-mesh sieve to obtain environmentally friendly organic fertilizer.

[0041] Example 2

[0042] A method for preparing an environmentally friendly organic fertilizer includes the following steps: Corn stalks and cottonseed cake were crushed separately using a pulverizer, and the particle size was controlled by a 5mm sieve. They were then mixed at a weight ratio of 2.5:1.2 to obtain an agricultural waste mixture. Bacillus subtilis was inoculated into LB liquid medium and cultured at 30℃ with shaking at 150 r / min for 24 h to activate one generation. The above operation was repeated three times to activate three generations. After three generations, the cells were collected by centrifugation at 8000 r / min for 10 min. The cells were resuspended in sterile glycerol-skimmed milk powder protectant (glycerol 10 wt%, skimmed milk powder 15 wt%), pre-frozen at -80℃ for 2 h, and then freeze-dried at -50℃ for 24 h to obtain Bacillus subtilis powder. Lactic acid bacteria were inoculated into MRS medium and incubated statically at 37℃ for 48 hours to activate one generation. The above operation was repeated three times for three generations of activation. After three generations, the bacterial cells were collected by centrifugation at 8000 r / min for 10 min. The cells were resuspended in sterile glycerol-skimmed milk powder protectant (10 wt% glycerol, 15 wt% skimmed milk powder), pre-frozen at -80℃ for 2 hours, and then freeze-dried at -50℃ for 24 hours to obtain lactic acid bacteria powder. Bacillus subtilis powder and lactic acid bacteria powder were mixed at a weight ratio of 2.7:1 to obtain a compound microbial agent. 62 parts by weight of agricultural waste mixture, 3.5 parts by weight of compound microbial agent, 3.5 parts by weight of functionalized biochar prepared in Preparation Example 2, and 1.2 parts by weight of oyster shell powder were placed in a mixer and stirred at 27 r / min for 20 min to obtain a mixture. The mixture was placed in a sealed fermentation tank with an initial packing density of 0.65 g / cm³. 3 The temperature was maintained at 46℃, and the headspace oxygen concentration was monitored by an oxygen sensor. When the oxygen concentration was below 3%, sterile air was introduced for 0.5 minutes to raise the oxygen concentration back to 3.5%, and this process was repeated every 48 hours. The pH of the material was adjusted to 6.6, and the fermentation cycle was 21 days. After fermentation, the material was transferred to a vacuum drying oven and dried for 9 hours at 41℃ and a vacuum of 5 kPa. After cooling to 25℃, the material was granulated through an 80-mesh sieve to obtain environmentally friendly organic fertilizer.

[0043] Example 3

[0044] A method for preparing an environmentally friendly organic fertilizer includes the following steps: Corn stalks and cottonseed cake were crushed separately using a pulverizer, and the particle size was controlled by a 5mm sieve. They were then mixed at a weight ratio of 3:1.7 to obtain an agricultural waste mixture. Bacillus subtilis was inoculated into LB liquid medium and cultured at 30℃ with shaking at 150 r / min for 24 h to activate one generation. The above operation was repeated three times to activate three generations. After three generations, the cells were collected by centrifugation at 8000 r / min for 10 min. The cells were resuspended in sterile glycerol-skimmed milk powder protectant (glycerol 10 wt%, skimmed milk powder 15 wt%), pre-frozen at -80℃ for 2 h, and then freeze-dried at -50℃ for 24 h to obtain Bacillus subtilis powder. Lactic acid bacteria were inoculated into MRS medium and incubated statically at 37℃ for 48 hours to activate one generation. The above operation was repeated three times for three generations of activation. After three generations, the bacterial cells were collected by centrifugation at 8000 r / min for 10 min. The cells were resuspended in a sterile glycerol-skimmed milk powder protectant (10 wt% glycerol and 15 wt% skimmed milk powder), pre-frozen at -80℃ for 2 hours, and then freeze-dried at -50℃ for 24 hours to obtain lactic acid bacteria powder. Bacillus subtilis powder and lactic acid bacteria powder were mixed at a weight ratio of 3:1 to obtain a compound microbial agent. 65 parts by weight of agricultural waste mixture, 4 parts by weight of compound microbial agent, 4 parts by weight of functionalized biochar prepared in Preparation Example 3, and 1.5 parts by weight of oyster shell powder were placed in a mixer and stirred at 30 r / min for 25 min to obtain a mixture. The mixture was placed in a sealed fermentation tank with an initial packing density of 0.65 g / cm³. 3The temperature was maintained at 47℃, and the headspace oxygen concentration was monitored by an oxygen sensor. When the oxygen concentration was below 3%, sterile air was introduced for 0.5 minutes to raise the oxygen concentration back to 4%, and this process was repeated every 48 hours. The pH of the material was adjusted to 6.8, and the fermentation cycle was 22 days. After fermentation, the material was transferred to a vacuum drying oven and dried for 10 hours at 43℃ and a vacuum of 5 kPa. After cooling to 25℃, the material was granulated through an 80-mesh sieve to obtain environmentally friendly organic fertilizer.

[0045] Example 4

[0046] A method for preparing an environmentally friendly organic fertilizer includes the following steps: Corn stalks and cottonseed cake were crushed separately using a pulverizer, and the particle size was controlled by a 5mm sieve. They were then mixed at a weight ratio of 3.5:2.0 to obtain an agricultural waste mixture. Bacillus subtilis was inoculated into LB liquid medium and cultured at 30℃ with shaking at 150 r / min for 24 h to activate one generation. The above operation was repeated three times to activate three generations. After three generations, the cells were collected by centrifugation at 8000 r / min for 10 min. The cells were resuspended in sterile glycerol-skimmed milk powder protectant (glycerol 10 wt%, skimmed milk powder 15 wt%), pre-frozen at -80℃ for 2 h, and then freeze-dried at -50℃ for 24 h to obtain Bacillus subtilis powder. Lactic acid bacteria were inoculated into MRS medium and incubated statically at 37℃ for 48 hours to activate one generation. The above operation was repeated three times for three generations of activation. After three generations, the bacterial cells were collected by centrifugation at 8000 r / min for 10 min. The cells were resuspended in sterile glycerol-skimmed milk powder protectant (10 wt% glycerol, 15 wt% skimmed milk powder), pre-frozen at -80℃ for 2 hours, and then freeze-dried at -50℃ for 24 hours to obtain lactic acid bacteria powder. Bacillus subtilis powder and lactic acid bacteria powder were mixed at a weight ratio of 3.2:1 to obtain a compound microbial agent. 68 parts by weight of agricultural waste mixture, 4.5 parts by weight of compound microbial agent, 4.5 parts by weight of functionalized biochar prepared in Preparation Example 4, and 1.8 parts by weight of oyster shell powder were placed in a mixer and stirred at 32 r / min for 30 min to obtain a mixture. The mixture was placed in a sealed fermentation tank with an initial packing density of 0.65 g / cm³. 3 The temperature was maintained at 48℃, and the headspace oxygen concentration was monitored by an oxygen sensor. When the oxygen concentration was below 3%, sterile air was introduced for 0.5 minutes to raise the oxygen concentration to 4.5%, and this process was repeated every 48 hours. The pH of the material was adjusted to 6.9, and the fermentation cycle was 23 days. After fermentation, the material was transferred to a vacuum drying oven and dried for 11 hours at 44℃ and a vacuum of 5 kPa. After cooling to 25℃, the material was granulated through an 80-mesh sieve to obtain environmentally friendly organic fertilizer.

[0047] Example 5

[0048] A method for preparing an environmentally friendly organic fertilizer includes the following steps: Corn stalks and cottonseed cake were crushed separately using a pulverizer, and the particle size was controlled by a 5mm sieve. They were then mixed at a weight ratio of 4:2.5 to obtain an agricultural waste mixture. Bacillus subtilis was inoculated into LB liquid medium and cultured at 30℃ with shaking at 150 r / min for 24 h to activate one generation. The above operation was repeated three times to activate three generations. After three generations, the cells were collected by centrifugation at 8000 r / min for 10 min. The cells were resuspended in sterile glycerol-skimmed milk powder protectant (glycerol 10 wt%, skimmed milk powder 15 wt%), pre-frozen at -80℃ for 2 h, and then freeze-dried at -50℃ for 24 h to obtain Bacillus subtilis powder. Lactic acid bacteria were inoculated into MRS medium and incubated statically at 37℃ for 48 hours to activate one generation. The above operation was repeated three times for three generations of activation. After three generations, the bacterial cells were collected by centrifugation at 8000 r / min for 10 min. The cells were resuspended in sterile glycerol-skimmed milk powder protectant (glycerol 10 wt%, skimmed milk powder 15 wt%), pre-frozen at -80℃ for 2 hours, and then freeze-dried at -50℃ for 24 hours to obtain lactic acid bacteria powder. Bacillus subtilis powder and lactic acid bacteria powder were mixed at a weight ratio of 3.5:1 to obtain a compound microbial agent. 70 parts by weight of agricultural waste mixture, 5 parts by weight of compound microbial agent, 5 parts by weight of functionalized biochar prepared in Preparation Example 5, and 2 parts by weight of oyster shell powder were placed in a mixer and stirred at 35 r / min for 35 min to obtain a mixture. The mixture was placed in a sealed fermentation tank with an initial packing density of 0.65 g / cm³. 3 The temperature was maintained at 50℃, and the headspace oxygen concentration was monitored by an oxygen sensor. When the oxygen concentration was below 3%, sterile air was introduced for 0.5 minutes to raise the oxygen concentration back to 5%, and this process was repeated every 48 hours. The pH of the material was adjusted to 7.0, and the fermentation cycle was 25 days. After fermentation, the material was transferred to a vacuum drying oven and dried for 12 hours at 45℃ and a vacuum of 5 kPa. After cooling to 25℃, the material was granulated through an 80-mesh sieve to obtain environmentally friendly organic fertilizer.

[0049] Comparative Example 1 A method for preparing an environmentally friendly organic fertilizer includes the following steps: The functionalized biochar prepared in Example 5 was replaced with the functionalized biochar prepared in Example 6, and all other operations were the same as in Example 5.

[0050] Comparative Example 2 A method for preparing an environmentally friendly organic fertilizer includes the following steps: The functionalized biochar prepared in Example 5 was replaced with the functionalized biochar prepared in Example 7, and all other operations were the same as in Example 5.

[0051] Comparative Example 3 A method for preparing an environmentally friendly organic fertilizer includes the following steps: The functionalized biochar prepared in Example 5 was replaced with the functionalized biochar prepared in Example 8, and all other operations were the same as in Example 5.

[0052] Comparative Example 4 A method for preparing an environmentally friendly organic fertilizer includes the following steps: The functionalized biochar prepared in Example 5 was replaced with the functionalized biochar prepared in Example 9, and all other operations were the same as in Example 5.

[0053] Comparative Example 5 A method for preparing an environmentally friendly organic fertilizer includes the following steps: Replace 5 parts by weight of the compound microbial agent in Example 5 with 5 parts by weight of Bacillus subtilis powder, and keep all other operations the same as in Example 5.

[0054] Performance testing The various properties of the environmentally friendly organic fertilizers prepared in Examples 1-5 and Comparative Examples 1-5 were tested using the following methods: Organic matter content: The content of organic matter in fertilizers was determined by the potassium dichromate method in order to assess the efficiency of waste resource conversion and its potential contribution to soil fertility. Total nitrogen, phosphorus, and potassium content: Total nitrogen was determined by the Kjeldahl method, total phosphorus by the molybdenum-antimony colorimetric method, and total potassium by the flame photometry method; the content of core nutrients in fertilizers was quantified to evaluate their direct fertilizer effect and nutrient balance. Microbial activity: The total number of Bacillus subtilis and lactic acid bacteria (CFU / g) in the environmentally friendly organic fertilizer was measured using the plate count method. Heavy metal safety: Atomic absorption spectrometry is used to measure the content of lead (Pb) and cadmium (Cd) to analyze the content of toxic heavy metals in fertilizers, so as to ensure that the products meet environmental safety standards and prevent soil pollution; Seed germination index (GI): Using the water extraction method and cucumber seeds as an indicator, the germination index GI = (seed germination rate × root length) / control group × 100% was calculated to assess the degree of fertilizer decomposition and plant toxicity, and to ensure its application safety. Plant growth experiment: A pot experiment was conducted in a greenhouse, using tomatoes as indicator plants to measure plant height and biomass (fresh weight). The soil was sandy loam, and the organic fertilizer application rate was 2 g / kg of soil. The culture period was 30 days. The actual promoting effect of fertilizer on crop growth was verified under controlled conditions, and its agricultural value was comprehensively evaluated. The test results are shown in Tables 1, 2 and 3.

[0055] Table 1. Organic matter content and core nutrient content Organic matter (%) Total nitrogen (g / kg) Total phosphorus (g / kg) Total potassium (g / kg) Example 1 45.2 12.5 8.1 9.3 Example 2 46.8 13.2 8.5 9.8 Example 3 48.1 14.0 9.0 10.2 Example 4 49.5 14.8 9.4 10.7 Example 5 50.3 15.5 9.9 11.0 Comparative Example 1 42.1 10.2 7.0 8.1 Comparative Example 2 40.5 9.8 6.5 7.8 Comparative Example 3 43.2 11.0 7.4 8.5 Comparative Example 4 44.0 11.5 7.8 8.9 Comparative Example 5 41.8 10.8 7.2 8.3 Table 2. Microbial activity and heavy metal safety <![CDATA[Microbial activity (CFU / g, × 10 7 )]]> Lead (mg / kg) Cadmium (mg / kg) Example 1 3.5 2.1 0.15 Example 2 4.2 1.9 0.14 Example 3 4.8 1.8 0.13 Example 4 5.3 1.7 0.12 Example 5 5.9 1.6 0.11 Comparative Example 1 2.8 2.5 0.18 Comparative Example 2 2.1 2.8 0.20 Comparative Example 3 3.0 2.3 0.17 Comparative Example 4 3.2 2.3 0.16 Comparative Example 5 2.5 2.4 0.19 Table 3. Seed germination index and plant growth experiment Seed germination index (%) Plant height (cm) Biomass (g / plant) Example 1 85.2 35.1 28.2 Example 2 87.6 36.8 30.2 Example 3 90.1 38.5 32.0 Example 4 92.5 40.2 33.8 Example 5 94.8 41.9 35.5 Comparative Example 1 78.5 32.0 25.1 Comparative Example 2 75.2 30.5 23.8 Comparative Example 3 80.1 33.2 26.0 Comparative Example 4 82.3 34.0 26.8 Comparative Example 5 77.8 31.8 24.9 (1) As can be seen from the test results in Tables 1-3, the environmentally friendly organic fertilizers prepared in Examples 1-5 of the present invention have good performance. Among them, Example 5 performed the best, with high organic matter content, high total nutrient content, strong microbial activity, low heavy metal content, and good seed germination index and plant growth indicators. However, the performance of the environmentally friendly organic fertilizers prepared in Comparative Examples 1-5 was reduced to varying degrees.

[0056] (2) The reason for the performance reduction of Comparative Example 1 may be the use of sawdust instead of bamboo as a raw material for biochar. There are significant differences in the chemical composition and physical structure of sawdust and bamboo. Bamboo has long fibers, dense structure and high silicon content. The biochar formed after pyrolysis usually has a more developed pore structure and higher mechanical strength. In contrast, the structure of sawdust biochar is relatively loose, and its specific surface area and porosity may be lower than that of bamboo charcoal. This leads to a decrease in its ability to act as a microbial carrier and nutrient adsorbent, which ultimately affects the stability of organic matter in fertilizer and the slow release effect of nutrients.

[0057] (3) The reason for the performance reduction in Comparative Example 2 may be the use of sulfuric acid instead of phosphoric acid for biochar activation. Sulfuric acid is a strong oxidizing acid, which may cause excessive corrosion and oxidation of the carbon skeleton of biochar during the treatment process, leading to the collapse or blockage of the pore structure; sulfuric acid will introduce sulfur elements in the form of sulfonic acid groups, etc. These sulfur-containing groups may have an inhibitory or toxic effect on the subsequently loaded Venetian nitric oxide bacteria and other microorganisms, significantly reducing the activity of microorganisms, thereby affecting the efficiency of the entire fermentation process and the final quality of the fertilizer.

[0058] (4) The reason for the performance degradation of Comparative Example 3 may be the use of a gelatin-gum arabic coating system instead of a chitosan-sodium alginate system. Chitosan-sodium alginate can form a high-strength, stable polyelectrolyte composite membrane through electrostatic interaction, which has good biocompatibility and controllable degradation. However, the gelatin-gum arabic composite generally has weaker film-forming properties and mechanical strength, and is more prone to breakage during freeze-drying and subsequent processing. It cannot provide effective protection for the encapsulated microorganisms, resulting in the death of a large number of cells during preparation and storage, thus rendering the "microbial warehouse" function of functionalized biochar ineffective.

[0059] (5) The reason for the reduced performance of Comparative Example 4 may be the use of rhizobia instead of Vignaland's nitrogen-fixing bacteria. Rhizobia are obligate symbiotic nitrogen-fixing microorganisms that live in symbiosis with legumes. Their nitrogen-fixing activity is highly dependent on the root nodule structure formed with specific legumes. In the corn stalk and cottonseed cake fermentation system of this invention, rhizobia cannot establish a symbiotic relationship, so their nitrogen-fixing ability cannot be activated and is almost ineffective. Vignaland's nitrogen-fixing bacteria, on the other hand, are free-living nitrogen-fixing bacteria that can independently fix nitrogen in soil and organic substrates, and their applicability is far wider than that of rhizobia. This substitution results in the nitrogen content in the fertilizer mainly depending on the raw materials themselves, and the additional nitrogen gain brought by nitrogen fixation disappears.

[0060] (6) The reason for the performance reduction of Comparative Example 5 may be the use of a single Bacillus subtilis inoculant instead of a compound microbial inoculant. Without the synergistic effect of lactic acid bacteria, the pH regulation ability of the fermentation system is weakened; Bacillus subtilis produces organic acids when rapidly decomposing organic matter, causing the pH of the system to drop rapidly; without lactic acid bacteria or other pH regulation mechanisms (it is difficult to completely and accurately control by external dripping alone), the overly acidic environment will in turn inhibit the activity of Bacillus subtilis itself, and even promote the growth of putrefactive bacteria, resulting in incomplete fermentation, nutrient loss and the production of unpleasant odors, ultimately reducing the quality and safety of the fertilizer.

[0061] (7) The bamboo-based biochar activated by phosphoric acid in this invention has a huge specific surface area and rich pore structure, which can not only adsorb nutrients and water, but also provide an ideal attachment point for microorganisms; the subsequent chitosan-sodium alginate coating forms microcapsules, which effectively protects the activity of microorganisms during freeze drying and fertilizer storage, so that they can slowly release and play a role after being applied to the soil; the biochar itself can regulate soil pH, and its porous structure can adsorb nutrients such as nitrogen and phosphorus, reduce loss, and achieve a slow release effect; the phosphorylation treatment further introduces phosphorus-containing functional groups, which enhances its binding ability with nutrient molecules; Bacillus spp. is good at secreting a variety of hydrolytic enzymes, which can quickly decompose the macromolecular organic matter in straw and cottonseed cake; lactic acid bacteria can effectively regulate the pH of the fermentation system by producing acid, inhibit the growth of harmful microorganisms, and create a suitable environment for other beneficial bacteria; by monitoring oxygen and pH and intervening during the fermentation process, the entire fermentation process is always in a highly efficient and safe aerobic-facultative anaerobic fermentation state, avoiding the odor and harmful substances produced in an anaerobic environment.

[0062] The embodiments described above provide a detailed explanation of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A method for preparing an environmentally friendly organic fertilizer, characterized in that, The preparation method includes the following steps: A mixture of crushed corn stalks and cottonseed cake is obtained by mixing them to produce an agricultural waste mixture. After Bacillus subtilis is activated for three generations, the bacterial cells are collected and freeze-dried to obtain Bacillus subtilis powder. Lactic acid bacteria were activated for three generations, and the bacterial cells were collected and freeze-dried to obtain lactic acid bacteria powder. A compound microbial agent is obtained by mixing Bacillus subtilis powder and lactic acid bacteria powder; A mixture of agricultural waste, compound microbial inoculants, functionalized biochar, and oyster shell powder is prepared. The mixture is fermented and dried in sequence to produce environmentally friendly organic fertilizer.

2. The method for preparing an environmentally friendly organic fertilizer as described in claim 1, characterized in that, The corn stalks and cottonseed cake are crushed and mixed at a weight ratio of 2~4:1~2.5; the weight ratio of Bacillus subtilis powder and lactic acid bacteria powder is 2.5~3.5:

1.

3. The method for preparing an environmentally friendly organic fertilizer as described in claim 1, characterized in that, The preparation method of the functionalized biochar includes the following steps: Bamboo is crushed and kept at 500℃ for 6 hours to obtain raw bamboo charcoal. Phosphorylated biochar was obtained by mixing and stirring raw bamboo char with 15 wt% phosphoric acid solution. Chitosan and 1 wt% acetic acid solution are mixed to obtain chitosan acetate solution, sodium alginate and deionized water are mixed to obtain sodium alginate aqueous solution, and chitosan acetate solution and sodium alginate aqueous solution are mixed to obtain coating solution; Phosphorylated biochar and coating solution were mixed and stirred, and then freeze-dried to obtain composite biochar. Functionalized biochar was prepared by mixing a suspension of Vignelandia diffusa and composite biochar, allowing it to stand, and then collecting the solid.

4. The method for preparing an environmentally friendly organic fertilizer as described in claim 3, characterized in that, The weight ratio of the original bamboo charcoal to 15wt% phosphoric acid solution is 10:80~100; the weight ratio of the chitosan to 1wt% acetic acid solution is 1.5~2:100; the weight ratio of the sodium alginate to deionized water is 1.5~2:100; and the weight ratio of the phosphorylated biochar to the coating solution is 10:80~100.

5. The method for preparing an environmentally friendly organic fertilizer as described in claim 3, characterized in that, The conditions for mixing and stirring the phosphorylated biochar and coating solution include a mixing temperature of 25°C and a mixing time of 30-60 min.

6. The method for preparing an environmentally friendly organic fertilizer as described in claim 3, characterized in that, The weight ratio of the Viñelandia diffusa suspension to the composite biochar is 1~1.5:

1.

7. The method for preparing an environmentally friendly organic fertilizer as described in claim 1, characterized in that, The weight ratio of the agricultural waste mixture, compound microbial agent, functionalized biochar, and oyster shell powder is 60~70:3~5:3~5:1~2.

8. The method for preparing an environmentally friendly organic fertilizer as described in claim 1, characterized in that, The fermentation conditions include a fermentation temperature of 45-50°C, an oxygen concentration of 3%-5%, a fermentation pH of 6.5-7.0, and a fermentation time of 20-25 days.

9. The method for preparing an environmentally friendly organic fertilizer as described in claim 1, characterized in that, The drying process includes a drying temperature of 40-45℃, a vacuum degree of ≤5kPa, and a drying time of 8-12h.

10. An environmentally friendly organic fertilizer, characterized in that, It is prepared by any one of the methods described in claims 1 to 9 for preparing an environmentally friendly organic fertilizer.