Special small molecule slow carbon bacterial fertilizer for crab culture and preparation method thereof

Abstract

The application discloses a kind of small molecule slow carbon bacterial fertilizer special for crab culture and a preparation method thereof, and belongs to the technical field of fertilizer preparation and aquaculture.The small molecule slow carbon bacterial fertilizer raw materials include, by weight: 60-70 parts of non-resistant chicken manure, 30-40 parts of corn bran, 5-10 parts of Sophora flavescens seedling, 0.2-0.4 parts of fermentation bacteria, 0.2-0.4 parts of EM bacteria, 0.3-0.5 parts of chitosan, 0.3-0.5 parts of seaweed extract, 4-6 parts of magnesium chloride hexahydrate, and 2-5 parts of diatomite.The preparation method includes raw material pretreatment, fermentation material mixing, fermentation, aging, crushing and screening, nutrient additive and EM bacteria addition, and packaging and storage.The application balances the carbon-nitrogen ratio, nitrogen-phosphorus ratio, calcium-magnesium ratio and silicon nutrients in water, constructs a "water grass-algae-microorganism" microecological balance system, inhibits green moss and blue algae, kills ciliates, proliferates beneficial bacteria, improves crab immunity, realizes water quality control, substrate improvement, water grass maintenance and growth promotion, and is suitable for crab pond mouth whole-cycle breeding, while realizing agricultural waste resource utilization.

Description

Technical Field

[0001] This invention relates to the fields of fertilizer preparation technology and aquaculture technology, specifically to a small molecule slow-carbon bacterial fertilizer for crab farming and its preparation method. Background Technology

[0002] 1. In the process of crab farming in ponds, the stability of the water environment, the fertility of the water and the balance of nutrients directly determine the survival rate, growth rate and quality of crabs. The healthy growth of aquatic plants can provide crabs with a habitat and molting environment, reduce stress response, and is the key to a high yield of crab farming. Currently, fertilizers used in crab pond farming are mainly divided into two categories: chemical fertilizers and traditional organic fertilizers. Although chemical fertilizers are fast-acting, they are single-nutrient, and long-term use can easily lead to eutrophication of pond water, causing cyanobacterial blooms, disrupting the micro-ecological balance of the water, increasing stress on crabs, reducing their immunity, and leading to frequent diseases such as soft shell disease and molting failure. They can also inhibit the growth of aquatic plants, causing root rot and damaging the crabs' habitat. Traditional organic fertilizers are mostly made by directly fermenting single animal manure, which has problems such as low nutrient utilization, incomplete fermentation, easy growth of harmful bacteria, and strong odor. They cannot specifically meet the differentiated needs of crabs for minerals and active substances during molting and growth periods, and it is difficult to meet the triple needs of pond water quality improvement, aquatic plant maintenance, and crab nutrition supplementation. Especially in extreme seasons such as low winter temperatures and high summer temperatures, the fertilizer effect is unstable and can easily cause losses in farming.

[0003] 2. Antibiotic-free chicken manure, as livestock and poultry manure without antibiotic residues, is rich in protein, amino acids, organic matter, and various minerals such as calcium and phosphorus. It is a high-quality organic fertilizer raw material that can provide sufficient nitrogen and organic matter for pond water, promote the growth of plankton, provide natural food for crabs (especially juvenile crabs), and at the same time, supplementing organic matter can improve the structure of pond bottom silt and reduce silt compaction.

[0004] 3. Corn bran is rich in cellulose, polysaccharides, and hemicellulose, making it a high-quality slow-release carbon source. Polysaccharides can serve as a stable soluble carbon source to replenish energy in water bodies and promote the proliferation of beneficial bacteria. Hemicellulose (mainly arabinoxylan) can be converted into xylooligosaccharides—a highly efficient prebiotic—after enzymatic hydrolysis, selectively promoting the growth of beneficial bacteria (such as Bacillus subtilis and lactic acid bacteria) while inhibiting harmful bacteria. However, conventional fermentation processes often overlook this value of corn bran: direct mixing with chicken manure for fermentation leads to the loss of polysaccharides due to high-temperature degradation, and the waste of hemicellulose due to ineffective conversion. This results in inefficient utilization of the carbon source in corn bran and difficulty in achieving carbon-nitrogen synergy.

[0005] 4. Substances such as chitosan oligosaccharides, seaweed extract, magnesium chloride hexahydrate, and diatomaceous earth have targeted effects in crab pond aquaculture. Among them, chitosan oligosaccharides can enhance crab immunity and inhibit the growth of harmful bacteria (such as Vibrio) at the bottom of the pond. Studies have shown that appropriate doses of chitosan oligosaccharides can increase the immune protection rate of crabs to over 62.5%, effectively reducing the incidence of diseases, and are especially suitable for use during the molting period of crabs. Seaweed extract can promote the growth of beneficial algae (such as diatoms and green algae) in the water, supplement active nutrients, and at the same time help the root growth of aquatic plants, enhancing... The aquatic plants' resilience reduces their decay during hot seasons; magnesium chloride hexahydrate precisely replenishes the magnesium ions needed for crab growth. Magnesium ions are a key element in crab shell formation, promoting shell hardening and reducing the incidence of soft-shell disease and molting failure, thus solving the common problem of molting difficulties in pond aquaculture; diatomaceous earth can adsorb residual feed, feces, and harmful substances such as heavy metals and ammonia nitrogen in the water, purifying the bottom sediment and water quality, improving the crab's habitat, and its porous structure can adsorb beneficial bacteria, extending the duration of bacterial effects.

[0006] 5. In addition, ciliate disease is a common parasitic disease in crab farming. Ciliates (such as Vorticella and Cyclops) often attach to the gills, appendages, and body surface of crabs, affecting their breathing, feeding, and molting. In severe cases, they can lead to suffocation or molting failure, causing significant economic losses to farmers. Traditional prevention and control methods often use chemical drugs such as zinc sulfate and copper sulfate. However, chemical drugs are prone to drug resistance, pollute water bodies, and have poor safety for juvenile crabs, which is inconsistent with the development trend of green and ecological aquaculture.

[0007] 6. In the early spring, when crab seedlings are initially released, the temperature is low (mostly between 0℃ and 10℃), which significantly inhibits the activity of algae and bacteria in the water. This makes it difficult to fertilize the pond and maintain fertility. Ordinary fertilizers either have a slow effect or exhibit inconsistent fertilization, failing to cultivate sufficient plankton (the core natural food for juvenile crabs) and failing to meet the basic nutritional needs of newly released juvenile crabs. This can easily lead to stress and insufficient feeding in juvenile crabs, directly affecting their survival rate. In the summer, when the water temperature in the pond rises, traditional fertilizers decompose rapidly, releasing large amounts of nitrogen and phosphorus nutrients, causing eutrophication and leading to blue-green algae blooms. This not only pollutes the water and reduces dissolved oxygen but also causes aquatic plants to rot, destroying the crabs' habitat and further exacerbating the risks of aquaculture.

[0008] Therefore, developing a scientifically formulated, nutrient-balanced, and residue-free microbial fertilizer that can improve pond water quality, purify the bottom sediment, and maintain aquatic plants, while also providing targeted nutrition for crabs at different growth stages, promoting crab growth, improving survival rate and quality, and having ciliate control effects, and being suitable for ponds in different seasons such as early spring low temperatures and summer high temperatures, has become an urgent technical problem to be solved in the current crab farming industry. Summary of the Invention

[0009] To address the shortcomings of existing crab farming fertilizers, such as their limited nutrient content, susceptibility to pond water pollution, poor adaptability to high and low temperatures, inability to meet the specific needs of crabs at different growth stages and for aquatic plant maintenance, lack of effective control measures against ciliate diseases, and the inability of existing fermentation processes to maximize the utilization of corn bran polysaccharides and hemicellulose, this invention provides a small-molecule slow-carbon microbial fertilizer specifically for crab farming and its preparation method. This involves pre-activating corn bran, optimizing the ratio of fermentation agents and fermentation parameters, and fermenting diatomaceous earth together with antibiotic-free chicken manure, corn bran, and Sophora flavescens seedlings. The antibiotic-free chicken manure... The slightly acidic environment promotes the partial decomposition of diatomaceous earth, realizing a dynamic carrier effect of "in-situ pore formation - synchronous adsorption - bacterial colonization". It retains the activity of polysaccharides and hemicellulose in corn bran to the greatest extent, converting them into prebiotics (xylooligosaccharides). It is scientifically formulated with antibiotic-free chicken manure, Sophora flavescens seedlings, fermentation bacteria, EM bacteria and a variety of nutritional aids to achieve a synergistic effect of balanced nutrient supply, water quality improvement, bottom purification, aquatic plant maintenance, disease control and crab growth promotion. It solves the problems of existing technologies, reduces pond farming costs, improves farming efficiency and is suitable for the whole cycle of crab farming.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: A type of small-molecule slow-carbon bacterial fertilizer for crab farming, the raw materials of which, by weight, include: 60-70 parts antibiotic-free chicken manure, 30-40 parts corn bran, 5-10 parts Sophora flavescens seedlings, 0.2-0.4 parts fermentation bacteria, 0.2-0.4 parts EM bacteria, 0.3-0.5 parts chitosan oligosaccharide, 0.3-0.5 parts seaweed extract, 4-6 parts magnesium chloride hexahydrate, and 2-5 parts diatomaceous earth.

[0011] The corn bran has a particle size of 10-20 mesh.

[0012] The grain size of the sophora flavescens seedlings is 10-20 mesh.

[0013] The fermentation bacteria are a complex microbial community, composed of Bacillus subtilis, Aspergillus niger, and photosynthetic bacteria in a weight ratio of 5:3:2, with a total number of the three bacteria (viable count) ≥1×10¹. 0 cfu / g.

[0014] The EM bacteria are a complex microbial community, composed of Bacillus subtilis, photosynthetic bacteria and nitrifying bacteria in a weight ratio of 5:3:2, with a total number of the three bacteria (live bacteria) ≥1×10¹¹cfu / g.

[0015] The chitosan oligosaccharide is β-1,4-oligo-glucosamine with a degree of polymerization n=2~20 and a purity ≥90%.

[0016] The seaweed extract is an extract of *Alternaria latifolia*, and its technical specifications include: alginic acid content ≥20%, organic matter content ≥40%, water solubility 100%, and dark brown powder.

[0017] The nitrifying bacteria are a mixture of nitrite-oxidizing bacteria and nitrate-oxidizing bacteria in a weight ratio of 2:1.

[0018] A method for preparing a small-molecule slow-carbon bacterial fertilizer specifically for crab farming includes the following steps: Step 1: Raw material pretreatment: (1) Corn bran pretreatment: Crush the corn bran to 10-20 mesh and screen to remove impurities; soak the screened corn bran in warm water at 30-35℃ for 12-24 hours, add water at 1.5 times the weight of the corn bran, add cellulase (0.1%-0.2% of the weight of the corn bran) for pre-activation treatment, and obtain activated corn bran for use. (2) Pretreatment of Sophora flavescens seedlings: Dry the Sophora flavescens seedlings, crush them to 10-20 mesh, screen to remove impurities, and set aside for later use; (3) Antibiotic-free chicken manure and diatomaceous earth can be used directly without additional pretreatment; Step 2: Mixing fermentation materials: (1) Pre-activation of microbial agent: Weigh the fermentation bacteria according to the weight parts, mix with the activated corn bran obtained in step 1.1, and activate for 3-6 hours; (2) General mixing: Weigh out the antibiotic-free chicken manure, diatomaceous earth, the mixture obtained in step 2.1, and Sophora flavescens seedlings by weight, mix them evenly, and adjust the moisture content of the materials to 50-60% to obtain the fermentation mixture; Step 3: Fermentation: Pile the fermentation mixture to a height of 1.8-2.0 meters and a width of 20 meters for aerobic fermentation. Temperature and oxygen levels are controlled throughout the process. Fermentation parameters are as follows: (1) Carbon-to-nitrogen ratio control: 25:1-30:1; (2) Medium temperature fermentation stage: 3-5 days, control the temperature at 35-45℃. For the first 2 days, the temperature can be briefly raised to 58-60℃ (not exceeding 60℃) to kill miscellaneous bacteria and insect eggs. Turn the mixture 1-2 times a day. (3) Low-temperature maturation stage: 7-10 days, cooling down to 25-30℃, slow maturation; (4) Maintain the oxygen concentration inside the pile at 12% by aeration through the aeration system, and adjust the aeration intensity in a timely manner to ensure stable oxygen concentration; Obtain the fermentation substrate; Step 4: Aging: Transfer the fermented base material to the aging workshop and age for 60 days; Step 5: Crushing and screening: Crushing and screening the aged material to remove coarse impurities; Step 6: Adding nutritional supplements and EM bacteria: Weigh out the chitosan oligosaccharide, seaweed extract, and magnesium chloride hexahydrate by weight, mix them evenly, and add them together with EM bacteria to the material obtained in Step 5. Mix evenly using a twin-shaft mixer to obtain a small molecule slow carbon microbial fertilizer for crab farming. Step 7: Packaging and storage: Seal the package and store in a cool, dry place.

[0019] Compared with the prior art, the present invention has the following beneficial effects: 1. Scientifically formulated with significant synergistic effects, suitable for the entire lifecycle of pond aquaculture: This invention uses antibiotic-free chicken manure and corn bran as base materials, with added fermentation bacteria, resulting in no antibiotic residues and providing abundant basic nutrients such as organic matter, nitrogen, and carbon. Through a specific ratio of antibiotic-free chicken manure to corn bran, the carbon-to-nitrogen ratio in the pond is precisely adjusted to an appropriate range (15:1-20:1). Simultaneously, nutrient supplements such as EM bacteria, chitosan oligosaccharides, seaweed extract, magnesium chloride hexahydrate, and diatomaceous earth are added. The synergistic effect of these ingredients not only solves the problem of single-ingredient nutrients but also achieves multiple benefits including "fertilizer supply + pond water quality control + bottom sediment purification + aquatic plant maintenance + crab immunity enhancement," making it suitable for the entire lifecycle of crab aquaculture, from juvenile to adult stages, as well as during periods of low temperatures in early spring and high temperatures in summer.

[0020] 2. Precisely balances multiple nutrient ratios in the pond to simultaneously meet the needs of aquatic plants, algae, and bottom sediment microorganisms, effectively inhibiting cyanobacterial blooms and algae growth: This invention, through scientific formulation, systematically balances the supply of key nutrients in the pond—carbon-nitrogen ratio, nitrogen-phosphorus ratio, calcium-magnesium ratio, and silicon—to simultaneously meet the differentiated needs of the three major biological groups, and achieves the dual effect of controlling cyanobacteria and inhibiting algae growth from an ecological competition perspective: (1) Adapting to the needs of aquatic plants (Elodea nuttallii): The slow-release carbon source provided by corn bran and the organic nitrogen source provided by antibiotic-free chicken manure form a suitable carbon-nitrogen ratio environment for the growth of Elodea nuttallii, promoting the development of the aquatic plant's root system and the growth of its stems and leaves, and enhancing its photosynthetic capacity. A robust aquatic plant community can absorb a large amount of nitrogen and phosphorus nutrients in the water, forming a nutrient competition with cyanobacteria. At the same time, it inhibits the photosynthesis of algae through shading, reducing the space for algae growth from the source. The corn bran is controlled to a particle size of 10-20 mesh, which can ensure the slow release of carbon source and avoid the bottom pollution caused by excessively fine powder depositing at the bottom of the pond.

[0021] (2) Adapting to the needs of beneficial algae (diatoms): Diatomite is rich in silicon, which can provide essential nutrients for diatoms and promote their proliferation. At the same time, by adjusting the carbon-nitrogen ratio and nitrogen-phosphorus ratio, beneficial algae such as diatoms and green algae can be cultivated in a targeted manner, giving them an advantage in the ecological competition with blue-green algae, thereby effectively inhibiting the outbreak of blue-green algae. The synergistic effect of seaweed extract and active substances produced by fermentation maintains the excellent water color of "fertile, lively, tender and refreshing", providing sufficient natural food for juvenile crabs.

[0022] (3) Adapting to the needs of bottom sediment microorganisms: Diatomaceous earth adsorbs organic matter and provides an attachment carrier for microorganisms. The EM bacteria (Bacillus subtilis, photosynthetic bacteria, and nitrifying bacteria) work synergistically with the abundant organic matter in the fermentation material to provide balanced nutrition (carbon source, nitrogen source, and minerals) for aerobic and facultative anaerobic microorganisms in the bottom sediment, promoting the efficient decomposition of organic matter at the bottom of the pond and reducing the accumulation of silt and the toxic and harmful substances produced by anaerobic fermentation. The improvement of the bottom sediment environment can reduce the germination rate of moss spores and further inhibit the growth of moss.

[0023] By simultaneously meeting the precise nutritional requirements of aquatic plants, algae, and microorganisms, this invention constructs a three-in-one pond micro-ecological balance system of "aquatic plants-algae-microorganisms". It works synergistically from three levels: nutrient competition, ecological occupation, and environmental improvement to achieve long-term control of blue-green algae and suppression of green algae, thereby achieving long-term stability of water quality and continuous improvement of bottom sediment from the root.

[0024] 3. Improve pond water quality, purify bottom sediment, and maintain aquatic ecological balance: Fermented antibiotic-free chicken manure and corn bran can slowly release nutrients, preventing eutrophication of pond water; diatomaceous earth can efficiently adsorb impurities, uneaten feed, feces, and harmful substances such as heavy metals, ammonia nitrogen, and nitrite in the water, purifying the pond bottom sediment; EM bacteria can regulate the micro-ecology of pond water, increase the number of beneficial bacteria, inhibit the growth of harmful bacteria such as Vibrio, stabilize the pH value of the water, improve water transparency, enhance the photosynthesis of aquatic plants, increase dissolved oxygen in the water, and provide an excellent pond living environment for crabs.

[0025] 4. Targeted nutritional supplementation to promote crab growth and improve aquaculture quality: Chitosan oligosaccharides can significantly increase the activity of immune-related enzymes in crabs, enhancing their immunity, especially suitable for the molting period; magnesium chloride hexahydrate precisely supplements the magnesium ions needed for crab growth, promotes shell hardening, and reduces the incidence of soft shell disease and molting failure; seaweed extract and fermented amino acids, small molecule peptides and other active substances can promote crab feeding and growth, improving crab size and meat quality.

[0026] 5. Unique preparation process, long-lasting and stable bacterial efficacy, and significantly improved product quality: This invention employs a series of refined processes, including soaking corn bran in warm water and pre-activating it with cellulase to gently activate the enzymatic hydrolysis potential of hemicellulose and promote polysaccharide dissolution; the fermentation bacteria are a compound of Bacillus subtilis, Aspergillus niger, and photosynthetic bacteria in a 5:3:2 ratio, which is first mixed with activated corn bran and activated for 3-6 hours to form a carbon-driven fermentation system. The complementary enzyme systems of Aspergillus niger and Bacillus subtilis efficiently decompose hemicellulose into xylooligosaccharides; simultaneously, diatomaceous earth is fermented together with antibiotic-free chicken manure, corn bran, and Sophora flavescens seedlings, utilizing the weakly acidic environment of the antibiotic-free chicken manure... The environment promotes partial decomposition of diatomaceous earth, creating pores in situ to expand the specific surface area. Simultaneously, it adsorbs small-molecule active substances produced during fermentation and provides an attachment carrier for the microbial community, forming a microbial-carrier complex. A two-step method of precise temperature control is employed: mesophilic fermentation (35-45℃, 3-5 days) and low-temperature maturation (25-30℃, 7-10 days). During the first two days, the temperature can be briefly raised to 58-60℃ to kill miscellaneous bacteria and insect eggs. An aeration system maintains an oxygen concentration of 12% to ensure sufficient aerobic fermentation. After fermentation, aging, and pulverization, nutrient additives such as chitosan oligosaccharides, seaweed extract, and magnesium chloride hexahydrate, along with EM bacteria, are added. The diatomaceous earth carrier then undergoes secondary adsorption to form a multi-level microbial-carrier system. Through this integrated process, the product of this invention, compared to traditional fermentation processes, features uniform particle size, a polysaccharide retention rate increased by over 30%, a prebiotic content increased by over 40%, and sustained microbial activity, achieving a synergistic unity of thorough material maturation and maximum retention of active ingredients.

[0027] 6. Green and environmentally friendly, with outstanding innovation: This invention uses three agricultural wastes—antibiotic-free chicken manure, corn bran, and Sophora flavescens seedlings—as core raw materials to achieve the resource recycling of waste; it adsorbs EM bacteria through the porous structure of diatomaceous earth to form a "bacteria-carrier" combination system, extending the duration of bacterial efficacy; the process parameters are clear, the process is controllable, and the product has strong practicality and competitiveness. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to specific embodiments. The following embodiments are only used to illustrate the present invention and are not intended to limit the scope of protection of the present invention. Example

[0029] A small-molecule slow-carbon bacterial fertilizer for crab farming, the raw materials of which, by weight, include: 60 parts antibiotic-free chicken manure, 30 parts corn bran, 5 parts Sophora flavescens seedlings, 0.2 parts fermentation bacteria, 0.2 parts EM bacteria, 0.3 parts chitosan oligosaccharide, 0.3 parts seaweed extract, 4 parts magnesium chloride hexahydrate, and 2 parts diatomaceous earth.

[0030] The corn bran has a particle size of 10-20 mesh; The grain size of the Sophora flavescens seedlings is 10-20 mesh; The fermentation bacteria are a complex microbial community, composed of Bacillus subtilis, Aspergillus niger, and photosynthetic bacteria in a weight ratio of 5:3:2, with a total number of the three bacteria (viable count) ≥1×10¹. 0 cfu / g; The EM bacteria are a complex microbial community, composed of Bacillus subtilis, photosynthetic bacteria and nitrifying bacteria in a weight ratio of 5:3:2, with a total number of the three bacteria (live bacteria) ≥1×10¹¹cfu / g; The chitosan oligosaccharide is β-1,4-oligo-glucosamine with a degree of polymerization n=2~20 and a purity ≥90%. The seaweed extract is an extract of *Alternaria latifolia*, and its technical specifications include: alginic acid content ≥20%, organic matter content ≥40%, water solubility 100%, and dark brown powder.

[0031] The preparation method is carried out according to the steps described in claim 9.

[0032] Application Results: The small-molecule slow-carbon bacterial fertilizer prepared in this embodiment was applied to crab farming ponds. During the complete farming cycle from juvenile crabs to adult crabs, it was applied every 7-15 days, with a dosage of 40-50 catties per acre each time. Observations were conducted throughout the entire farming cycle. Compared with traditional organic fertilizers, the water transparency in the ponds increased by 20%, the incidence of ciliate disease decreased by 25%, the survival rate of juvenile crabs (juvenile crabs) increased by 15%, the incidence of soft-shell disease decreased by 10%, the average size of adult crabs increased by 10%, the survival rate of aquatic plants increased by 18%, and the farming efficiency increased by 10%, effectively solving the problems of insufficient feed and frequent disease outbreaks during the farming process. Example

[0033] A small-molecule slow-carbon bacterial fertilizer for crab farming, the raw materials of which, by weight, include: 65 parts antibiotic-free chicken manure, 35 parts corn bran, 8 parts Sophora flavescens seedlings, 0.3 parts fermentation bacteria, 0.3 parts EM bacteria, 0.4 parts chitosan oligosaccharide, 0.4 parts seaweed extract, 5 parts magnesium chloride hexahydrate, and 3 parts diatomaceous earth.

[0034] The corn bran has a particle size of 10-20 mesh; The grain size of the Sophora flavescens seedlings is 10-20 mesh; The fermentation bacteria are a complex microbial community, composed of Bacillus subtilis, Aspergillus niger, and photosynthetic bacteria in a weight ratio of 5:3:2, with a total number of the three bacteria (viable count) ≥1×10¹. 0 cfu / g; The EM bacteria are a complex microbial community, composed of Bacillus subtilis, photosynthetic bacteria and nitrifying bacteria in a weight ratio of 5:3:2, with a total number of the three bacteria (live bacteria) ≥1×10¹¹cfu / g; The chitosan oligosaccharide is β-1,4-oligo-glucosamine with a degree of polymerization n=2~20 and a purity ≥90%. The seaweed extract is an extract of *Alternaria latifolia*, and its technical specifications include: alginic acid content ≥20%, organic matter content ≥40%, water solubility 100%, and dark brown powder.

[0035] The preparation method is carried out according to the steps described in claim 9.

[0036] Application Results: The small-molecule slow-carbon bacterial fertilizer prepared in this embodiment was applied to crab farming ponds. It was applied every 7-15 days throughout the entire farming cycle from juvenile crabs to adult crabs, at a rate of 40-50 catties per acre each time. Observations were conducted throughout the entire farming cycle. Compared with traditional organic fertilizers, the pond water transparency increased by 20%, the incidence of ciliate disease decreased by 30%, the survival rate of juvenile crabs (juvenile crabs) increased by 20%, the incidence of soft-shell disease decreased by 13%, the average size of adult crabs increased by 15%, the survival rate of aquatic plants increased by 20%, and the farming efficiency increased by 15%. Furthermore, the adult crab meat was firmer and had improved taste, meeting the standards for green aquatic products. Example

[0037] A small-molecule slow-carbon bacterial fertilizer for crab farming, the raw materials of which, by weight, include: 70 parts antibiotic-free chicken manure, 40 parts corn bran, 10 parts Sophora flavescens seedlings, 0.4 parts fermentation bacteria, 0.4 parts EM bacteria, 0.5 parts chitosan oligosaccharide, 0.5 parts seaweed extract, 6 parts magnesium chloride hexahydrate, and 5 parts diatomaceous earth.

[0038] The corn bran has a particle size of 10-20 mesh; The grain size of the Sophora flavescens seedlings is 10-20 mesh; The fermentation bacteria are a complex microbial community, composed of Bacillus subtilis, Aspergillus niger, and photosynthetic bacteria in a weight ratio of 5:3:2, with a total number of the three bacteria (viable count) ≥1×10¹. 0 cfu / g; The EM bacteria are a complex microbial community, composed of Bacillus subtilis, photosynthetic bacteria and nitrifying bacteria in a weight ratio of 5:3:2, with a total number of the three bacteria (live bacteria) ≥1×10¹¹cfu / g; The chitosan oligosaccharide is β-1,4-oligo-glucosamine with a degree of polymerization n=2~20 and a purity ≥90%. The seaweed extract is an extract of *Alternaria latifolia*, and its technical specifications include: alginic acid content ≥20%, organic matter content ≥40%, water solubility 100%, and dark brown powder.

[0039] The preparation method is carried out according to the steps described in claim 9.

[0040] Application Results: The small-molecule slow-carbon bacterial fertilizer prepared in this embodiment was applied to crab farming ponds. During the complete farming cycle from juvenile crabs to adult crabs, it was applied every 7-15 days, with a dosage of 40-50 catties per acre each time. Observations were conducted throughout the entire farming cycle. Compared with traditional organic fertilizers, the water transparency in the ponds increased by 20%, the incidence of ciliate disease decreased by 28%, the survival rate of juvenile crabs (juvenile crabs) increased by 18%, the incidence of soft-shell disease decreased by 15%, the average size of adult crabs increased by 20%, the survival rate of aquatic plants increased by 25%, and the farming efficiency increased by 20%. This effectively solved the problems of difficulty in fertilizing the water, short-lasting fertilizer effect, and aquatic plant maintenance during low-temperature periods, achieving stable water quality and healthy crab growth throughout the year.

[0041] Based on the above embodiments, it can be seen that the present invention proposes a small molecule slow-carbon bacterial fertilizer for crab farming and its preparation method. This small-molecule slow-release microbial fertilizer for crab farming uses antibiotic-free chicken manure, corn bran, and Sophora flavescens seedlings as base materials. Diatomaceous earth is fermented together with the base materials. The weakly acidic environment of the antibiotic-free chicken manure promotes the partial decomposition of diatomaceous earth, achieving a dynamic carrier effect of "in-situ pore creation - synchronous adsorption - microbial colonization". At the same time, the corn bran is pre-activated and a special fermentation bacteria compounded with Bacillus subtilis, Aspergillus niger, and photosynthetic bacteria is added. The precise temperature control process of "medium-temperature fermentation + low-temperature maturation" maximizes the preservation of the polysaccharide and hemicellulose activity in the corn bran and converts them into prebiotics (xylooligosaccharides). Then, EM bacteria compounded with Bacillus subtilis, photosynthetic bacteria, and nitrifying bacteria are added, as well as nutritional aids such as chitosan oligosaccharide, seaweed extract, and magnesium chloride hexahydrate, forming a five-in-one synergistic system of "organic slow-release carbon source + functional microorganisms + targeted nutrients + plant-derived insecticidal components + prebiotic enhancement". By precisely balancing the carbon-nitrogen ratio, nitrogen-phosphorus ratio, calcium-magnesium ratio, and silicon supply in the pond, the nutritional needs of aquatic plants (Elodea nuttallii), beneficial algae (diatoms), and bottom sediment microorganisms are simultaneously met, constructing a micro-ecological balance system of "aquatic plants-algae-microorganisms," effectively inhibiting cyanobacterial blooms and algae growth. At the same time, the addition of Sophora flavescens seedlings endows the microbial fertilizer with the effect of killing ciliates. The optimized corn bran process and the diatomaceous earth carrier effect together endow the microbial fertilizer with the dual value of "stabilizing water and improving bottom," achieving multiple functions of water quality regulation, bottom sediment purification, aquatic plant maintenance, disease control, and crab growth promotion. It is suitable for the complete breeding cycle of crabs from juvenile to adult, reducing breeding costs and improving breeding efficiency and product quality.

[0042] The embodiments of the present invention have been described above. However, the embodiments are not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make more specific implementation methods under the guidance of the present embodiments, all of which are within the protection scope of the present invention.

Claims

1. A small-molecule slow-carbon bacterial fertilizer specifically for crab farming, characterized in that, The raw materials, by weight, include: 60-70 parts antibiotic-free chicken manure, 30-40 parts corn bran, 5-10 parts Sophora flavescens seedlings, 0.2-0.4 parts fermentation bacteria, 0.2-0.4 parts EM bacteria, 0.3-0.5 parts chitosan oligosaccharide, 0.3-0.5 parts seaweed extract, 4-6 parts magnesium chloride hexahydrate, and 2-5 parts diatomaceous earth.

2. The small-molecule slow-carbon bacterial fertilizer for crab farming according to claim 1, characterized in that, The corn bran has a particle size of 10-20 mesh.

3. The small-molecule slow-carbon bacterial fertilizer for crab farming according to claim 1, characterized in that, The grain size of the sophora flavescens seedlings is 10-20 mesh.

4. The small-molecule slow-carbon bacterial fertilizer for crab farming according to claim 1, characterized in that, The fermentation bacteria are a complex microbial community, composed of Bacillus subtilis, Aspergillus niger, and photosynthetic bacteria in a weight ratio of 5:3:2, with a total number of the three bacteria (viable count) ≥1×10¹. 0 cfu / g.

5. The small-molecule slow-carbon bacterial fertilizer for crab farming according to claim 1, characterized in that, The EM bacteria are a complex microbial community, composed of Bacillus subtilis, photosynthetic bacteria and nitrifying bacteria in a weight ratio of 5:3:2, with a total number of the three bacteria (live bacteria) ≥1×10¹¹cfu / g.

6. The small-molecule slow-carbon bacterial fertilizer for crab farming according to claim 1, characterized in that, The chitosan oligosaccharide is β-1,4-oligo-glucosamine with a degree of polymerization n=2~20 and a purity ≥90%.

7. The small-molecule slow-carbon bacterial fertilizer for crab farming according to claim 1, characterized in that, The seaweed extract is an extract of *Alternaria latifolia*, and its technical specifications include: alginic acid content ≥20%, organic matter content ≥40%, water solubility 100%, and dark brown powder.

8. The small-molecule slow-carbon bacterial fertilizer for crab farming according to claim 5, characterized in that, The nitrifying bacteria are a mixture of nitrite-oxidizing bacteria and nitrate-oxidizing bacteria in a weight ratio of 2:

1.

9. A method for preparing a small-molecule slow-carbon bacterial fertilizer for crab farming as described in claims 1-8, characterized in that, Includes the following steps: Step 1: Raw material pretreatment: (1) Corn bran pretreatment: Crush the corn bran to 10-20 mesh and screen to remove impurities; soak the screened corn bran in warm water at 30-35℃ for 12-24 hours, add water at 1.5 times the weight of the corn bran, add cellulase (0.1%-0.2% of the weight of the corn bran) for pre-activation treatment, and obtain activated corn bran for use. (2) Pretreatment of Sophora flavescens seedlings: Dry the Sophora flavescens seedlings, crush them to 10-20 mesh, screen to remove impurities, and set aside for later use; (3) Antibiotic-free chicken manure and diatomaceous earth can be used directly without additional pretreatment; Step 2: Mixing fermentation materials: (1) Pre-activation of microbial agent: Weigh the fermentation bacteria according to the weight parts, mix with the activated corn bran obtained in step 1.1, and activate for 3-6 hours; (2) General mixing: Weigh out the antibiotic-free chicken manure, diatomaceous earth, the mixture obtained in step 2.1, and Sophora flavescens seedlings by weight, mix them evenly, and adjust the moisture content of the materials to 50-60% to obtain the fermentation mixture; Step 3: Fermentation: The fermentation mixture is piled up to a height of 1.8-2.0 meters and a width of 20 meters for aerobic fermentation. Temperature and oxygen are controlled throughout the process, and the fermentation parameters are controlled as follows: (1) Carbon-to-nitrogen ratio control: 25:1-30:1; (2) Medium temperature fermentation stage: 3-5 days, control the temperature at 35-45℃. For the first 2 days, the temperature can be briefly raised to 58-60℃ (not exceeding 60℃) to kill miscellaneous bacteria and insect eggs. Turn the mixture 1-2 times a day. (3) Low-temperature maturation stage: 7-10 days, cooling down to 25-30℃, slow maturation; (4) Maintain the oxygen concentration inside the pile at 12% by aeration through the aeration system, and adjust the aeration intensity in a timely manner to ensure stable oxygen concentration; Obtain the fermentation substrate; Step 4: Aging: Transfer the fermented base material to the aging workshop and age for 60 days; Step 5: Crushing and screening: Crushing and screening the aged material to remove coarse impurities; Step 6: Adding nutritional supplements and EM bacteria: Weigh out the chitosan oligosaccharide, seaweed extract, and magnesium chloride hexahydrate by weight, mix them evenly, and add them together with EM bacteria to the material obtained in Step 5. Mix evenly using a twin-shaft mixer to obtain a small molecule slow carbon microbial fertilizer for crab farming. Step 7: Packaging and storage: Seal the package and store in a cool, dry place.