Method for preparing organic compound fertilizer by combining hermetia illucens faeces and trichoderma

Abstract

The invention relates to a method for preparing an organic compound fertilizer by combining hermetia illucens faeces and trichoderma, which comprises the following steps: S1, pretreating the hermetia illucens faeces to obtain pretreated hermetia illucens faeces; s2, mixing the pretreated hermetia illucens faeces with auxiliary materials, and adjusting the water content of the materials; s3, inoculating trichoderma into the mixed material, and carrying out aerobic fermentation; s4, performing screening, nutrient enrichment and granulation on the fermentation product to obtain the organic compound fertilizer; wherein organic matters and nutrient elements are provided through the black soldier fly feces, the trichoderma promotes decomposition of the organic matters in the fermentation process and endows the organic compound fertilizer with a biological prevention and control function, and nutrition supply and disease prevention and control functions of the organic compound fertilizer are achieved through the synergistic effect of the black soldier fly feces and the trichoderma. The method aims to prepare the organic compound fertilizer with dual functions of nutrition supply and biological control of soil-borne diseases so as to meet the requirements of modern agriculture on efficient, green and sustainable fertilizers.

Description

Technical Field

[0001] The invention relates to the technical field of organic compound fertilizer preparation, in particular to a method for preparing organic compound fertilizer by combining black soldier fly feces with Trichoderma. Background Art

[0002] In the context of modern agriculture and sustainable development, organic fertilizer has received increasing attention as an important soil conditioner and source of plant nutrition. Organic fertilizer not only provides nutrients necessary for crop growth but also improves soil structure, enhances soil fertility, and increases soil biological activity, playing a vital role in achieving green agricultural development and protecting the environment.

[0003] Black soldier fly (Hermetia illucens) larvae are highly efficient bioconverters, capable of bioconverting organic waste such as food waste, livestock and poultry manure, and crop straw. Their larvae can serve as a high-protein feed resource, and their digestion product—black soldier fly feces—is a high-quality organic fertilizer. Rich in organic matter, nitrogen, phosphorus, potassium, and various trace elements, black soldier fly feces is a natural slow-release fertilizer that slowly releases nutrients to meet crop growth needs and has the potential to improve soil physical and chemical properties. Therefore, black soldier fly feces presents broad application prospects in the field of organic fertilizer preparation.

[0004] However, pure black soldier fly manure fertilizer still has certain limitations in terms of functionality. In the existing technology, in order to improve the fertilizer efficiency and function of black soldier fly manure fertilizer, the following improvement directions are usually adopted:

[0005] Direction 1: Combination with humic acid substances. Humic acid is an important component of soil organic matter and has many functions such as improving soil structure, increasing nutrient utilization, and promoting plant growth. The combination of black soldier fly feces with humic acid substances (such as fulvic acid, biological humic acid, etc.) can synergistically improve the soil improvement and nutrient supply capacity of fertilizers. For example, by mixing humic acid with black soldier fly feces for fermentation or directly mixing and granulating, an organic fertilizer product rich in humic acid can be prepared. However, this method mainly focuses on improving the physical and chemical properties and nutrient content of fertilizers, and has limited effect on solving soil-borne disease problems.

[0006] Direction 2: Combination with microbial agents (such as Bacillus subtilis). Microbial agents play an important role in agricultural production. Some beneficial microorganisms, such as Bacillus subtilis, can secrete phospholytic enzymes, potassium-soluble enzymes, proteases, etc., promote the transformation and release of soil nutrients, and improve the absorption and utilization rate of nutrients by plants. Combining black soldier fly feces with agents such as Bacillus subtilis can enhance the nutrient supply capacity of fertilizers and the soil improvement effect. For example, microbial organic fertilizers can be prepared by inoculating Bacillus subtilis during the fermentation process of black soldier fly feces, or adding Bacillus subtilis agents during the post-processing stage of fertilizers. However, the functions of agents such as Bacillus subtilis are mainly concentrated in nutrient transformation and plant growth promotion. Although some strains also have certain biocontrol capabilities, their effectiveness and broad spectrum in preventing and controlling soil-borne diseases are relatively limited.

[0007] Direction three: Combination with chemical additives. In order to quickly increase the nutrient content of fertilizers, especially the content of large elements such as nitrogen, phosphorus and potassium, some technical solutions will add chemical fertilizers to black soldier fly manure fertilizers, such as urea, diammonium phosphate, potassium chloride, etc. By adding chemical fertilizers, the nutrient index of fertilizers can be quickly improved to meet the needs of certain crops with high nutrient requirements. However, this method is essentially a simple physical mixing of organic fertilizers and chemical fertilizers. Although it can increase the nutrient content, it does not give full play to the soil improvement and long-term fertilizer supply advantages of organic fertilizers, and over-reliance on chemical fertilizers is also contrary to the development concept of green agriculture. In addition, the introduction of chemical additives may also reduce the quality and environmental friendliness of organic fertilizer products.

[0008] While existing technologies have made some progress in improving the fertilizer efficiency of black soldier fly manure fertilizers, the following significant shortcomings remain: 1. Relatively limited functionality: Existing improved manure fertilizers still primarily focus on providing nutrients necessary for crop growth. While they can improve soil physical and chemical properties and promote plant growth to a certain extent, they are insufficient for biological control of soilborne diseases. With continuous cropping and the long-term use of chemical fertilizers and pesticides, soilborne diseases are becoming increasingly serious and have become a major constraint on agricultural production. Therefore, there is an urgent need to develop organic fertilizers that combine the dual functions of nutrient supply and biological control. 2. Insufficient stress resistance: Existing manure fertilizers, even when combined with certain beneficial microbial agents, have relatively limited biological control effects, a narrow inhibitory spectrum against soilborne pathogens, and unstable control effects. Crops treated with these fertilizers remain vulnerable to soilborne pathogens, especially during high-incidence seasons or in continuously cropped areas. The risk of disease remains high, impacting crop yield and quality. 3. Fermentation efficiency still has room for improvement: Some existing methods for preparing insect manure fertilizers have long fermentation cycles, resulting in incomplete decomposition of organic matter and slow nutrient release, limiting the potential for improving fertilizer effectiveness. Improving fermentation efficiency and shortening the fermentation cycle while ensuring full decomposition of organic matter and efficient nutrient release are pressing technical challenges.

[0009] Trichoderma spp. is a type of fungus widely found in nature. It has been proven to be a highly effective, broad-spectrum, and safe biocontrol fungus with enormous potential for application in agricultural biocontrol. Trichoderma has the ability to decompose complex organic matter such as cellulose, hemicellulose, and chitin, promoting the composting of organic waste and the release of nutrients. More importantly, Trichoderma has significant antagonistic and inhibitory effects on a variety of plant pathogens, effectively controlling a variety of soil-borne diseases such as root rot, wilt, and damping-off. Furthermore, Trichoderma can produce plant growth hormones, promoting plant growth and development, and increasing crop yield and quality.

[0010] However, there are no systematic reports on the effective combination of Trichoderma and black soldier fly feces to produce an organic compound fertilizer with both nutritional and disease-resistant properties. How to effectively combine the biocontrol advantages of Trichoderma with the nutritional advantages of black soldier fly feces to develop a new, more comprehensive organic compound fertilizer product to meet modern agriculture's demand for green, efficient, and sustainable fertilizers has become a key technical challenge urgently needed by those skilled in the art. Summary of the Invention

[0011] In order to solve the technical problems existing in the prior art, the present invention provides a method for preparing an organic compound fertilizer by combining black soldier fly feces with Trichoderma, aiming to overcome the technical defects of existing insect feces fertilizers such as single function and low fermentation efficiency, and prepare an organic compound fertilizer with the dual functions of nutrient supply and biological control of soil-borne diseases, so as to meet the demand of modern agriculture for efficient, green and sustainable fertilizers.

[0012] The present invention discloses a method for preparing an organic compound fertilizer by combining black soldier fly feces with Trichoderma, comprising the following steps:

[0013] S1. Pretreat the black soldier fly excrement to obtain pretreated black soldier fly excrement. This step is the first link in the method flow, and its technical purpose is to ensure the smooth progress of the subsequent fermentation process and the quality of the final fertilizer product. As the product of black soldier fly larvae treating organic waste, black soldier fly excrement may contain a high amount of water in its initial state, which is not conducive to microbial fermentation. Pretreatment, such as natural air drying, low-temperature drying, centrifugal dehydration or mechanical filtration, is intended to reduce the moisture content of black soldier fly excrement to a suitable level (for example, a moisture content of ≤20%), thereby creating an environment more suitable for microbial growth and facilitating subsequent material mixing operations. The black soldier fly excrement obtained by pretreatment provides a preliminarily optimized matrix raw material for subsequent steps;

[0014] S2. Mix the pretreated black soldier fly excrement with auxiliary materials and adjust the moisture content of the materials. Step S2 follows step S1, and the pretreated black soldier fly excrement is physically mixed with the auxiliary materials. The introduction of auxiliary materials has multiple technical considerations: first, auxiliary materials such as straw powder or pine sawdust can adjust the carbon-nitrogen ratio of the mixture to make it more in line with the needs of microbial fermentation and provide a balanced ratio of carbon and nitrogen sources for microorganisms; second, auxiliary materials can improve the permeability of the material, increase the pore space, provide sufficient oxygen for aerobic microorganisms, and avoid the occurrence of anaerobic fermentation; third, auxiliary materials can serve as a carrier for microbial growth and provide a larger surface area. While mixing the materials, this step also emphasizes the precise adjustment of the moisture content of the mixture. Adjusting the moisture content to an appropriate range (for example, 45%-55%) is a key factor in ensuring that subsequent microorganisms can grow and ferment efficiently. Too high or too low a moisture content will inhibit microbial activity, affecting fermentation efficiency and the quality of the final fertilizer product. Therefore, step S2 constructs an excellent physical and chemical environment for the subsequent microbial inoculation and fermentation steps by mixing materials and adjusting the moisture content;

[0015] S3. Inoculate Trichoderma into the mixture for aerobic fermentation. Step S3 is a key step in this method and the core innovation of the technical solution. In this step, a Trichoderma agent with efficient biocontrol functions is inoculated into the mixture prepared in step S2. As a functional microorganism, Trichoderma plays a crucial role in this step: on the one hand, Trichoderma can secrete abundant extracellular enzymes, which accelerate the decomposition and conversion of organic matter in the mixture, improve fermentation efficiency, promote nutrient release, and provide a foundation for the nutritional function of the final fertilizer product; on the other hand, during its growth and metabolism, Trichoderma can produce a variety of antibiotics and competitive substances, effectively inhibiting the growth and reproduction of pathogens in the soil, thereby giving the final fertilizer product the function of biological control of soil-borne diseases. Step S3 clearly states that "aerobic fermentation" must be carried out, emphasizing that the fermentation process needs to be carried out under conditions of sufficient oxygen. This is conducive to the growth and reproduction of aerobic microorganisms such as Trichoderma, maximizing their effectiveness in decomposing organic matter and biological control. To ensure an aerobic environment, a dynamic composting system is usually required, and the oxygen concentration in the compost is maintained through measures such as ventilation and turning. The dynamic composting system also helps control the fermentation temperature, maintaining a temperature range suitable for Trichoderma growth and further optimizing the fermentation process;

[0016] S4, the fermentation product is screened, nutritionally fortified and granulated to obtain an organic compound fertilizer. Step S4 is a post-processing process for the fermentation product, which aims to further improve the quality and performance of the fertilizer product. First, a screening operation is performed to remove coarse impurities in the fermentation product and improve the uniformity and appearance quality of the product; secondly, nutritional fortification is performed, and appropriate nutritional additives such as potassium dihydrogen phosphate and trace elements can be added as needed to further increase the nutrient content of the fertilizer to meet the nutrient requirements of different crops; finally, granulation treatment is performed to make the powdered or bulk fermentation product into granular fertilizer, which is convenient for storage, transportation and application, improves the convenience of fertilizer use, and improves the uniformity of fertilization. After processing in step S4, an organic compound fertilizer product with good physical properties and stable nutrient content is finally obtained;

[0017] Among them, the black soldier fly excrement provides organic matter and nutrients, the Trichoderma promotes the decomposition of organic matter during the fermentation process and gives the organic compound fertilizer a biological control function, and the synergistic effect of the black soldier fly excrement and Trichoderma realizes the nutrient supply and disease control function of the organic compound fertilizer. Specifically, step S1 provides a qualified raw material matrix for the subsequent steps; step S2, based on S1, builds a suitable environment for microbial fermentation by mixing auxiliary materials and adjusting the moisture content; step S3 is the core fermentation step, which uses the biological activity of Trichoderma to convert the raw materials into a semi-finished fertilizer with specific functions; step S4 carries out fine processing of the fermentation semi-finished product, and finally obtains an organic compound fertilizer product that meets the application requirements. Throughout the entire process, the synergistic effect of black soldier fly excrement and Trichoderma runs through: black soldier fly excrement provides organic matter and basic nutrients, and Trichoderma decomposes organic matter, releases nutrients, and gives the fertilizer a biological control function during the fermentation process. The two complement each other's advantages and jointly improve the comprehensive performance of the fertilizer product.

[0018] According to the method for preparing organic compound fertilizer by combining black soldier fly excrement with Trichoderma, in step S1, the pretreatment of the black soldier fly excrement includes a drying treatment, and the drying treatment is selected from natural air drying at an ambient temperature of 25-30°C for 2-3 days or low-temperature drying in an oven at 50-60°C for 8-12 hours, until the moisture content of the black soldier fly excrement is no more than 20%; when the initial moisture content of the black soldier fly excrement is high, centrifugal dehydration at 3000 rpm for 10 minutes or mechanical pressure filtration pre-dehydration at 0.5-0.8 MPa is performed before the drying treatment; the amount of the black soldier fly excrement used is 40%-60% of the total amount of the formula.

[0019] The above proposal first clarifies that drying is a key technical feature of pretreatment, and specifically defines two drying methods: air drying and low-temperature drying. Air drying is limited to 2-3 days at an ambient temperature of 25-30°C under well-ventilated conditions, while low-temperature drying is limited to 8-12 hours in an oven at 50-60°C. These temperature and time parameters are selected based on the characteristics of black soldier fly feces and the need to protect microbial activity. Excessively high temperatures may cause the loss of some nutrients in the feces or hinder the subsequent growth of Trichoderma, while excessively low temperatures or short drying times may not effectively reduce the moisture content of the feces. Keeping the moisture content below 20% is crucial to ensure uniform mixing of the subsequent materials and promote smooth aerobic fermentation. Excessively high moisture content impairs material permeability, easily leading to anaerobic fermentation, unpleasant odors, and reduced fermentation efficiency. Furthermore, the proposal stipulates that when the initial moisture content of the black soldier fly feces is high, pre-dehydration treatment such as centrifugal dehydration or mechanical filtration may be performed. This is because in actual production, the initial moisture content of black soldier fly feces may vary depending on the source and treatment method. If dried directly, the drying time and energy consumption will increase significantly. Therefore, adding a pre-dehydration step, such as centrifugal dehydration at 3000rpm for 10 minutes or mechanical filtration at 0.5-0.8MPa, can effectively and quickly reduce the initial moisture content of the feces, improve subsequent drying efficiency, and reduce overall energy consumption. In addition, the amount of black soldier fly feces is also limited to 40%-60% of the total formula. This dosage range is obtained through experimental exploration and optimization by the inventor. It can not only ensure that the organic fertilizer product contains sufficient organic matter and nutrients, but also take into account the regulatory role of auxiliary materials and maintain the good physical and chemical properties of the fermentation system. If the amount of black soldier fly feces is too low, the fertilizer efficiency of the organic fertilizer may be insufficient; if the amount is too high, it may cause an imbalance in the carbon-nitrogen ratio of the fermentation material or reduce the permeability. Therefore, the dosage range of 40%-60% is the optimal range for black soldier fly feces to play its matrix role.

[0020] According to the method for preparing an organic compound fertilizer by combining black soldier fly feces with Trichoderma, in step S2, the auxiliary material is selected from straw powder, pine sawdust or a combination thereof, and the amount of the auxiliary material added is 30%-50% of the total formula; the particle size of the straw powder is not greater than 2 cm, the carbon-nitrogen ratio of the pine sawdust is 25-30, and the particle diameter is 0.5-2 cm; and the moisture content of the auxiliary material before use is less than 15%.

[0021] In the above scheme, it is first clearly pointed out that the auxiliary materials can be selected from straw powder, pine sawdust or a combination thereof, and the amount of auxiliary materials added is limited to 30%-50% of the total formula. The addition of auxiliary materials plays a vital role in the method of the present invention, and its main function is to adjust the carbon-nitrogen ratio of the fermentation material and improve the permeability. Although black soldier fly feces are rich in organic matter and nutrients, their carbon-nitrogen ratio is relatively low. Fermentation alone may lead to insufficient carbon source, affecting the normal metabolism of microorganisms and the full decomposition of organic matter. Straw powder and pine sawdust, as commonly used agricultural waste and wood processing by-products, have the advantages of moderate carbon-nitrogen ratio, wide sources, and low cost. They can effectively supplement the carbon source, balance the carbon-nitrogen ratio of the fermentation material, provide microorganisms with sufficient carbon skeleton and energy source, and promote the effective decomposition and conversion of organic matter. In addition, it is further limited that the particle size of straw powder is not more than 2 cm, the carbon-nitrogen ratio of pine sawdust is 25-30, the particle diameter is 0.5-2 cm, and the moisture content of the auxiliary materials before use is less than 15%. The setting of these parameters is based on the physical properties of the auxiliary materials and the fermentation requirements. If the particle size of the straw powder is too large, it will be difficult to mix evenly with the insect manure, affecting the uniformity and efficiency of the fermentation; the carbon-nitrogen ratio of pine sawdust is limited to 25-30 to ensure that it can effectively supplement the carbon source while avoiding nitrogen loss caused by an excessively high carbon-nitrogen ratio; the diameter of pine sawdust particles is 0.5-2cm, which can effectively increase the porosity of the material, improve permeability, and provide sufficient oxygen for aerobic microorganisms; the moisture content of the auxiliary material before use is less than 15%, which helps to control the overall moisture content of the mixed material within an appropriate range. Therefore, the selection of auxiliary materials, the amount of addition, and the limitation of physical properties in this plan jointly ensure that the fermentation material has a suitable carbon-nitrogen ratio and permeability, creating favorable conditions for the subsequent effective inoculation of Trichoderma and efficient fermentation.

[0022] According to the method for preparing an organic compound fertilizer by combining black soldier fly excrement with Trichoderma, in step S2, the pretreated black soldier fly excrement is mixed with auxiliary materials in a ratio of 6:4; the mixing is carried out using a horizontal spiral mixer or a dedicated compost turning machine with a rotation speed of 15-20 rpm; and an appropriate amount of water is evenly sprayed through a sprayer to adjust the moisture content of the mixed material to 45-55%.

[0023] In the above scheme, it is first specifically stipulated that the pretreated black soldier fly excrement and the auxiliary materials are mixed in a ratio of 6:4. This ratio is further optimized based on the 40%-60% amount of excrement and 30%-50% amount of auxiliary materials in the previous step. The 6:4 ratio can better balance the nutritional value of the excrement and the adjustability of the auxiliary materials, achieving the best fermentation effect and product quality. The mixing method is also specified, preferably using a horizontal spiral mixer or a dedicated compost turning machine with a rotation speed of 15-20rpm. Horizontal spiral mixers and compost turning machines are commonly used material mixing equipment that can achieve rapid and uniform mixing of materials. Controlling the rotation speed at 15-20rpm can not only ensure mixing efficiency, but also avoid material crushing or energy loss caused by excessive rotation speed. The use of uniform mixing can ensure that the excrement and auxiliary materials are in full contact, providing a basis for the subsequent uniform inoculation and full action of Trichoderma. In addition, it is also specified that an appropriate amount of water is evenly sprayed through a sprinkler to adjust the moisture content of the mixed material to 45-55%. Moisture content is one of the key factors affecting aerobic fermentation. If the moisture content is too low, the activity of microorganisms will decrease and fermentation will be slow; if the moisture content is too high, the permeability of the material will be poor, an anaerobic environment will easily form, unpleasant odors will be generated, and fermentation efficiency will be affected. The moisture content of 45-55% is an appropriate range verified by experiments. It can not only meet the growth and metabolic needs of microorganisms, but also ensure good permeability of the material and promote the smooth progress of aerobic fermentation. The use of a sprinkler to evenly spray water can avoid excessive or insufficient local moisture and ensure the uniformity and stability of the overall moisture content of the mixed material. Therefore, this scheme further optimizes the operation of step S2 by precisely defining the mixing ratio, mixing equipment and moisture content adjustment method, providing a guarantee for the effective inoculation and efficient fermentation of subsequent Trichoderma.

[0024] According to the method for preparing organic compound fertilizer by combining black soldier fly feces with Trichoderma, in step S3, the Trichoderma is selected from Trichoderma harzianum or Trichoderma viride, and its spore concentration is not less than 1×10 8 CFU / g; the inoculation amount of the Trichoderma is 1%-3% of the total material; the inoculation method is selected from evenly spreading dry powder or spraying a suspension mixed with water in a ratio of 1:10; avoid temperatures above 35°C or direct sunlight during the inoculation process.

[0025] The above scheme first clarifies the selection of Trichoderma species, preferably Trichoderma harzianum or Trichoderma viride. Trichoderma harzianum and Trichoderma viride are the two most commonly used biocontrol bacteria in the Trichoderma genus, with multiple functions such as efficient decomposition of organic matter, inhibition of plant pathogens, and promotion of plant growth. The selection of these two Trichoderma species can fully utilize the biological control and growth promotion effects of Trichoderma, giving the organic compound fertilizer product excellent functionality. At the same time, the scheme also stipulates that the spore concentration of the Trichoderma agent should not be less than 1×10 8CFU / g. Spore concentration is an important indicator of inoculant activity. A high spore concentration ensures that Trichoderma quickly colonizes and functions in the fermentation material after inoculation, ensuring fermentation efficiency and product quality. The inoculum size is further limited to 1%-3% of the total material volume, with a preferred inoculum size of 2%. The inoculum size is a key parameter influencing fermentation efficiency and product cost. If the inoculum size is too low, the initial Trichoderma population will be insufficient, making it difficult for the fungus to quickly establish a dominant position, resulting in poor fermentation results. If the inoculum size is too high, production costs will increase and may lead to an overcrowded population, affecting bacterial viability. The inoculum size of 1%-3% is an optimal range determined through experimental optimization, ensuring effective Trichoderma colonization and function while balancing production costs. An inoculum size of 2% is preferred, achieving the optimal balance between efficiency and cost. Furthermore, the inoculation method is specified, which can be selected from evenly spreading a dry powder or spraying a suspension mixed with water at a 1:10 ratio. Dry powder application is easy to apply and suitable for large-scale production, while suspension spraying improves the uniform dispersion of the inoculant and ensures sufficient contact between the Trichoderma fungus and the material. Both inoculation methods have their own advantages and can be selected based on actual production conditions and equipment. Furthermore, the protocol emphasizes avoiding temperatures exceeding 35°C and direct sunlight during the inoculation process to protect the activity of the Trichoderma fungus. High temperatures and direct sunlight can adversely affect the viability of Trichoderma spores and even cause the fungus to die, thereby reducing the effectiveness of the inoculation. Therefore, taking necessary protective measures during the inoculation process is crucial to ensuring the activity of the Trichoderma fungus and the fermentation effect.

[0026] According to the method for preparing an organic compound fertilizer by combining black soldier fly feces with Trichoderma, in step S3, the aerobic fermentation includes a dynamic composting stage and a post-ripening stage; the dynamic composting stage is carried out using a closed dynamic composting system, the compost temperature is controlled at 45-55°C, the oxygen concentration is not less than 15%, the compost is turned once a day, and the dynamic composting stage lasts for 7 days.

[0027] The above proposal first clarifies that aerobic fermentation consists of two sequential processes: a dynamic composting phase and a post-ripening phase. The dynamic composting phase is the primary stage of fermentation, designed to achieve rapid decomposition and maturation of organic matter through rapid temperature increase and high temperature maintenance, while simultaneously killing pathogens and parasite eggs. The proposal specifies that the dynamic composting phase be conducted using a closed dynamic composting system. This closed system provides better control over the fermentation environment, reduces odor emissions, meets environmental requirements, and improves fermentation efficiency. It further specifies that the temperature during the dynamic composting phase be controlled at 45-55°C, with an oxygen concentration of no less than 15%, and that the compost be turned daily for seven days. A temperature range of 45-55°C is the optimal growth range for mesophilic microorganisms (including Trichoderma), promoting rapid reproduction and activity, and promoting the effective decomposition of organic matter. This temperature range is also sufficient to effectively kill most plant pathogens and parasite eggs, improving the hygienic and safe performance of the fertilizer. An oxygen concentration of no less than 15% is essential for the smooth progress of aerobic fermentation. The metabolism of aerobic microorganisms requires an adequate supply of oxygen. Too low an oxygen concentration will inhibit the activity of aerobic microorganisms and even lead to anaerobic fermentation and the production of unpleasant odors. Turning the compost once a day can increase the oxygen concentration in the pile and make the temperature evenly distributed, avoiding the generation of local high temperatures or anaerobic areas, and ensuring the uniformity and efficiency of fermentation. The dynamic composting stage lasts for 7 days, which is an appropriate time verified by experiments. It can not only ensure the initial decomposition and sanitary safety of organic matter, but also shorten the fermentation cycle and improve production efficiency. Therefore, this program constructs an efficient and controllable dynamic composting process by precisely defining the fermentation stage, fermentation system, temperature control, oxygen concentration control, turning frequency and fermentation time, providing a basis for further stabilization in the subsequent post-ripening stage.

[0028] According to the method for preparing organic compound fertilizer by combining black soldier fly feces with Trichoderma, in the after-ripening stage, the pile is transferred to a well-ventilated semi-open area for after-ripening fermentation, and is left to ferment for 5 days, during which the pile is turned every 2 days. The judgment criteria for the end of the after-ripening stage are: the pile temperature is stable below 35°C, the pile is dark brown, has no obvious odor, the pile material structure is loose, can be squeezed into a ball but is not sticky, and the carbon-nitrogen ratio is less than 20.

[0029] From the above scheme, it can be seen that the after-ripening stage is carried out after the dynamic composting stage, which aims to further stabilize the organic matter, reduce the composting temperature, and promote the further growth and function of Trichoderma. This scheme stipulates that the pile body will be transferred to a well-ventilated semi-open area for after-ripening fermentation in the after-ripening stage. A well-ventilated environment is conducive to heat dissipation and water evaporation, and the semi-open area can prevent rainwater from intruding while maintaining a certain degree of air permeability. The after-ripening stage is static fermentation for 5 days, during which the pile is turned every 2 days. Static fermentation helps microorganisms to further decompose and transform the difficult-to-decompose organic matter remaining in the dynamic composting stage, making the organic matter more stable and mature. Turning the pile every 2 days can maintain the air permeability of the pile body, promote the activity of aerobic microorganisms, and avoid overheating of the pile body. The 5-day after-ripening time is an appropriate time verified by experiments, which can ensure the full stabilization of organic matter without excessively extending the fermentation cycle. The above scheme also defines the criteria for judging the end of the post-ripening stage, including five aspects: ① The temperature of the pile is stable below 35°C, indicating that the fermentation process is basically complete and microbial activity has decreased; ② The pile is dark brown, which is a typical characteristic of fully mature organic matter; ③ The pile has no obvious odor, indicating that the fermentation process is good and no anaerobic fermentation occurs; ④ The pile material has a loose structure and can be squeezed into a ball without being sticky, reflecting the appropriate maturity and moisture content of the material; ⑤ The carbon-nitrogen ratio is less than 20, which is an important indicator of compost maturity and indicates that the organic matter has been effectively converted and is suitable for plant absorption and utilization. These five criteria complement each other and together constitute the comprehensive basis for judging the end of the post-ripening stage, ensuring that the fermentation products meet the requirements of stability, maturity, and harmlessness, and providing a foundation for the preparation and application of subsequent products.

[0030] According to a method for preparing an organic compound fertilizer by combining black soldier fly feces with Trichoderma, in step S4, the screening is performed using a rotary screening machine or a vibrating screen with an aperture of 1 cm, and the screening speed is controlled at 30-50 rpm; the nutritional fortification comprises adding potassium dihydrogen phosphate in an amount of 2‰ of the mass of the fermentation product and trace elements in an amount of 0.5‰ of the mass of the fermentation product to the fermentation product after screening, wherein the trace elements are a mixture of ferrous sulfate, zinc sulfate, and copper sulfate in a ratio of 1:1:1.

[0031] The above scheme defines the first two steps of step S4, "Screening, fortifying, and granulating the fermentation product," namely screening and fortification. Screening is the first step in post-processing, intended to remove coarse impurities, such as uncomposted straw and sawdust, from the fermentation product, improving the product's uniformity and applicability. This scheme specifies that screening should be performed using a rotary screener or vibrating screener with a 1 cm aperture, with a screening speed controlled at 30-50 rpm. A 1 cm sieve aperture effectively removes most coarse impurities while preventing the loss of fine particles, ensuring product yield and quality. Rotary screeners and vibrating screens are commonly used screening equipment, capable of efficient material screening. A screening speed controlled at 30-50 rpm ensures screening efficiency while preventing material damage or equipment wear caused by excessive speed. The screened coarse material can be returned to the next fermentation batch for reuse, improving raw material utilization and reducing production costs. Furthermore, fortification is the second step in post-processing, intended to further enhance the fertilizer's nutrient content and functionality to meet crop growth requirements. The scheme stipulates that nutritional fortification includes adding potassium dihydrogen phosphate and trace elements to the fermentation product after screening. Potassium dihydrogen phosphate, as a high-quality phosphorus and potassium fertilizer, can effectively supplement phosphorus and potassium elements, increase the phosphorus and potassium content of the fertilizer, and meet the crops' needs for phosphorus and potassium. Trace elements are essential nutrients for crop growth, but the demand is relatively small and they are usually easily deficient in the soil. The scheme prefers to add a mixture of ferrous sulfate, zinc sulfate, and copper sulfate as trace elements, and limits the mixing ratio to 1:1:1, with a total amount of 0.5‰ of the fermentation product mass. These trace elements are common limiting trace elements in crop growth. Adding them in appropriate amounts can effectively supplement soil trace elements, improve the comprehensive nutritional value of the fertilizer, and promote healthy crop growth. At the same time, the scheme also limits the amount of potassium dihydrogen phosphate to 2‰ of the fermentation product mass. The determination of these nutritional fortification components and amounts is an optimized selection based on weighing the fertilizer nutrient improvement effect and production cost, aiming to achieve effective fertilizer nutrient improvement at a lower cost.

[0032] According to the method for preparing an organic compound fertilizer by combining black soldier fly feces with Trichoderma, in step S4, the granulation is carried out using a disc granulator with a rotation speed of 15-20 rpm and an inclination angle of 45-50° or an extrusion granulator with a die hole diameter of 2-4 mm, and 1-2% starch or molasses is added as a binder during the granulation process to form granules with a diameter of 2-5 mm; the granulated product is dried, and the drying treatment is selected from natural airing with a spreading thickness of no more than 5 cm, turning 2-3 times a day, and drying for 2-3 days under sunny conditions, or hot air drying at a temperature of 60-70°C, a wind speed of 1.5-2.0 m / s, and a drying time of 4-6 hours, until the moisture content is no more than 15%.

[0033] The above scheme defines the final steps in step S4, namely granulation and drying. Granulation is the process of converting powdered or bulk fertilizer into granules. The granulated fertilizer has advantages such as good fluidity, easy application, and slow nutrient release, making it more conducive to mechanized fertilization and crop absorption and utilization. This scheme specifies that granulation be performed using a disc granulator with a rotation speed of 15-20 rpm and an inclination angle of 45-50°, or an extrusion granulator with a die hole diameter of 2-4 mm. Disc granulators and extrusion granulators are commonly used organic fertilizer granulation equipment and can efficiently convert powdered materials into granules. Controlling the rotation speed and inclination angle, as well as defining the die hole diameter, are important parameters for ensuring granulation quality and particle size uniformity. This scheme also specifies the addition of 1-2% starch or molasses as a binder during the granulation process. Starch and molasses are commonly used organic binders that can improve the cohesiveness of the material and promote granule formation and stability. Controlling the addition amount to 1-2% ensures effective granulation without excessively increasing production costs or affecting fertilizer quality. The diameter of the granules produced after granulation is 2-5 mm, an appropriate size for organic fertilizer particles, making them convenient for application and facilitating slow nutrient release. The above solution further stipulates that the granulated product must be dried, with options for natural air drying or hot air drying. Natural air drying is a low-cost drying method suitable for dry climates or seasons, but the drying cycle is longer and significantly affected by weather. This solution stipulates that the thickness of the granules spread out during natural air drying should not exceed 5 cm, with the granules turned 2-3 times daily and dried for 2-3 days on sunny days to improve drying efficiency and uniformity. Hot air drying is a highly efficient drying method with a short drying cycle and minimal weather impact, but it also carries higher equipment and energy costs. This solution specifies a hot air drying temperature of 60-70°C, a wind speed of 1.5-2.0 m / s, and a drying time of 4-6 hours. These parameters are optimized to ensure both drying efficiency and product quality. The ultimate goal of drying is to control the product's moisture content to no more than 15%. A low moisture content prevents fertilizer caking and mildew, extending shelf life and ensuring product quality. Therefore, this solution, through precise definition of granulation equipment, binder, granulation parameters, and drying methods, establishes an efficient and feasible granulation and drying process, ultimately producing a granular organic compound fertilizer product that meets application requirements.

[0034] According to the method for preparing an organic compound fertilizer by combining black soldier fly feces with Trichoderma, the pH value of the organic compound fertilizer is 6.5-7.5; the heavy metal content of the organic compound fertilizer is: cadmium content is not more than 0.8 mg / kg, lead content is not more than 25 mg / kg; the number of viable Trichoderma in the organic compound fertilizer is not less than 1×10 6 CFU / g.

[0035] The above scheme limits the quality indicators of the final prepared organic compound fertilizer product, ensuring the quality and safety of the product from three aspects: pH value, heavy metal content and the number of live Trichoderma. The scheme limits the pH value of the organic compound fertilizer to 6.5-7.5. This pH range is close to neutral, which is suitable for the growth of most crops. It is also conducive to the activity of soil microorganisms and improves the utilization rate of fertilizers. Too high or too low pH values will have an adverse effect on crop growth and soil environment. The heavy metal content of organic compound fertilizers is also limited, with cadmium content not exceeding 0.8 mg / kg and lead content not exceeding 25 mg / kg. These heavy metal limit values are in compliance with the provisions of the national organic fertilizer standard NY 525-2021 "Organic Fertilizer", ensuring that the product is safe and pollution-free and will not cause heavy metal pollution risks to soil and crops. In addition, the number of live Trichoderma in organic compound fertilizers is limited to not less than 1×10 6 CFU / g. The viable count of Trichoderma is an important indicator for measuring the biological control function of organic compound fertilizers. Maintaining a high viable count of Trichoderma ensures that after the product is applied to the soil, Trichoderma can quickly colonize and exert its biological control function, inhibiting the growth of soil-borne pathogens and protecting crops from soil-borne diseases. 1×10 6 The viable bacterial count (CFU / g) is the minimum requirement for ensuring the product's biocontrol effectiveness. Therefore, by limiting the product's pH value, heavy metal content, and viable Trichoderma count, this solution ensures the quality, safety, and functionality of the final organic compound fertilizer from multiple dimensions, demonstrating the advantages of the preparation method and product characteristics of the present invention.

[0036] The method of preparing organic compound fertilizer by combining black soldier fly excrement with Trichoderma can produce the following technical effects:

[0037] 1. Effectively improve the nutritional function of organic compound fertilizer: Black soldier fly feces itself is rich in organic matter and nutrients, providing basic nutrients for fertilizer. During the fermentation process, Trichoderma can secrete a variety of extracellular enzymes such as cellulase, hemicellulase, and pectinase, which can efficiently decompose the complex organic matter in the feces and auxiliary materials, and convert organic nutrients into inorganic nutrients that are more easily absorbed and utilized by plants, such as converting organic nitrogen into ammonium nitrogen and nitrate nitrogen, and converting organic phosphorus into phosphates. In addition, the metabolic activities of Trichoderma can also produce a variety of plant growth stimulants, such as indoleacetic acid (IAA), gibberellins (GA), cytokinins (CTK), etc., which promote plant root development and nutrient absorption, thereby significantly improving the nutritional supply capacity of organic compound fertilizer and providing sufficient nutrient guarantee for crop growth.

[0038] 2. Imparting significant biocontrol capabilities to organic compound fertilizers: Trichoderma, as a highly effective biocontrol fungus, possesses multiple biocontrol mechanisms. First, Trichoderma can inhibit the colonization and growth of pathogens by competing for nutrients and ecological niches. Second, Trichoderma can produce hydrolases such as chitinase and glucanase, which directly cleave the cell walls of pathogens and kill them. Third, Trichoderma can produce a variety of antibiotics, such as trichodermin and harzianidin, to inhibit the growth of pathogens. Furthermore, Trichoderma can induce resistance in plants, enhancing their own defenses against pathogen infection. By introducing Trichoderma into the preparation of organic compound fertilizers and maintaining its activity in the fermentation product, the final organic compound fertilizer product can effectively prevent and control soil-borne diseases, reduce the use of chemical pesticides, and achieve healthy crop growth.

[0039] 3. Improve the fermentation efficiency and production efficiency of organic compound fertilizer: The efficient decomposition ability of Trichoderma can accelerate the decomposition process of organic waste and shorten the fermentation cycle. The dynamic composting system and the control of aerobic fermentation conditions further optimize the fermentation environment, promote the rapid growth and reproduction of microorganisms such as Trichoderma, and improve fermentation efficiency. Compared with traditional natural composting or static composting, the dynamic composting combined with the fermentation method of Trichoderma inoculation adopted in the present invention can significantly shorten the fermentation time, increase the output of fertilizer per unit time, and enhance production efficiency.

[0040] 4. Improved safety of organic compound fertilizer products: The high-temperature aerobic fermentation process effectively kills pathogens, parasite eggs, and weed seeds that may be present in black soldier fly feces, improving the hygienic safety of the fertilizer product. Furthermore, the present method primarily utilizes biological methods, avoiding the excessive use of chemical additives and reducing the chemical risks of the fertilizer product, making the final organic compound fertilizer product safer, more reliable, and more environmentally friendly.

[0041] 5. Achieve synergistic effects between nutrient supply and disease control: This invention cleverly integrates nutrient supply and biological control functions. Through the synergistic effect of black soldier fly feces and Trichoderma, it achieves "one-time fertilization, dual benefits." While providing the nutrients necessary for crop growth, organic compound fertilizers can also effectively prevent and control soil-borne diseases, reduce disease occurrence, lower planting risks, and improve crop yield and quality. This synergistic effect between nutrition and disease control makes the organic compound fertilizer prepared by this invention have higher application value and market competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 Table 1 of the embodiment of the present invention reflects the effects of different treatments on the main agronomic traits of green sugar beet hearts;

[0044] Figure 2 Table 2 of the embodiment of the present invention reflects the effects of different treatments on the yield of green sugar beet hearts;

[0045] Figure 3 Table 3 of the embodiment of the present invention is the repeated data of main agronomic traits;

[0046] Figure 4 Table 4 of the embodiment of the present invention is a test report of bio-organic fertilizer;

[0047] Figure 5 It is a flow chart of the preparation method of the present invention. DETAILED DESCRIPTION

[0048] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0049] like Figure 5 As shown, this embodiment provides a method for preparing an organic compound fertilizer by combining black soldier fly excrement with Trichoderma, and through the synergistic effect of black soldier fly excrement and Trichoderma, the dual functions of nutrient supply and disease prevention and control of the organic compound fertilizer are achieved.

[0050] 1. Raw Materials Preparation

[0051] 1.1 Black soldier fly feces

[0052] The black soldier fly feces used in this example are derived from organic waste such as kitchen waste, livestock and poultry manure, or agricultural waste, produced through the biotransformation of black soldier fly (Hermetia illucens) larvae. This feces is rich in organic matter and various nutrients and is a key raw material for preparing organic compound fertilizer. In this example, the black soldier fly feces used in this formulation account for 50% of the total weight of the formula.

[0053] 1.2 Trichoderma

[0054] In this example, Trichoderma harzianum was used as the fungus agent, and its spore concentration was 2×10 8 CFU / g. This Trichoderma agent is a commercially available "Green Health" brand Trichoderma agent. Trichoderma is used as a functional bacteria to improve the efficiency of organic matter decomposition and provide biological control capabilities.

[0055] 1.3 Auxiliary materials

[0056] In this example, straw powder is used as the auxiliary material. The straw powder is obtained by grinding dry rice straw into a particle size no larger than 2 cm. The straw powder has a moisture content of 12% and is used to adjust the carbon-nitrogen ratio and permeability of the material. In this example, the straw powder is used in an amount of 40% of the total formulation.

[0057] 1.4 Nutritional additives

[0058] This embodiment uses potassium dihydrogen phosphate (purity ≥98%, particle size ≤1mm) and a trace element mixture (ferrous sulfate, zinc sulfate, and copper sulfate mixed in a 1:1:1 ratio, all with a purity ≥98%) as nutrient additives to increase the nutrient content of the fertilizer.

[0059] 2. Process steps

[0060] 2.1 Pretreatment of Black Soldier Fly Feces (Corresponding to Step S1)

[0061] First, the moisture content of the collected black soldier fly feces was measured using a drying method (drying at 105°C to constant weight), which revealed an initial moisture content of 65%. Due to the high moisture content, the feces were pre-dehydrated using centrifugal dehydration. Specifically, the feces were placed in a centrifuge and centrifuged at 3000 rpm for 10 minutes.

[0062] After pre-dehydration, the excrement was placed in an oven at 50-60°C for low-temperature drying for 10 hours. After drying, the moisture content was measured again to confirm that the moisture content had dropped to 18%, meeting the requirement of no more than 20%.

[0063] The pretreatment process loosens the excrement, facilitating subsequent fermentation. This process effectively reduces the moisture content of the black soldier fly excrement while preserving the beneficial microorganisms and nutrients to the greatest extent possible.

[0064] 2.2 Mixing and moisture content adjustment (corresponding to step S2)

[0065] The pretreated black soldier fly feces and straw powder were mixed at a mass ratio of 6:4. In this embodiment, a horizontal spiral mixer was used for mixing, with the speed set at 18 rpm and the mixing time set at 15 minutes to ensure uniform mixing of the materials.

[0066] After mixing, the handheld material test method was used to initially determine that the moisture content of the mixture was low. Based on experience, to promote microbial growth and metabolism, the moisture content must be adjusted to an appropriate range. Therefore, a sprayer was used to evenly apply an appropriate amount of water to adjust the moisture content of the mixture to 50% (within the range of 45-55%). The adjusted moisture content was reconfirmed by drying.

[0067] Appropriate moisture content is an important guarantee for the growth of Trichoderma and the degradation of organic matter. Too low moisture content will limit the activity of microorganisms, while too high moisture content will lead to anaerobic conditions and affect the fermentation effect.

[0068] 2.3 Trichoderma inoculation (corresponding to step S3)

[0069] The Trichoderma agent was measured at a ratio of 2% (within the range of 1%-3%) of the total amount of the material. Inoculation was performed by evenly spreading the dry powder, specifically by evenly spreading the measured Trichoderma agent on the surface of the mixed material, and then mixing it for 10 minutes using a horizontal spiral mixer (speed 15 rpm) to ensure that the Trichoderma agent and the material were fully mixed.

[0070] The inoculation process was carried out at room temperature (25°C), avoiding temperatures above 35°C or direct sunlight to ensure the activity of the Trichoderma. The selection of the Trichoderma inoculum size was based on experimental optimization results, which not only ensured sufficient bacteria to exert the biological control function but also controlled production costs.

[0071] 2.4 Aerobic fermentation (corresponding to step S3)

[0072] Aerobic fermentation includes dynamic composting stage and post-ripening stage, as follows:

[0073] 2.4.1 Dynamic composting stage

[0074] The inoculated material is placed in a closed dynamic composting system for fermentation. The system is built with a steel frame and consists of a closed fermentation tank with a size of 4m long × 2m wide × 1.5m high. Ventilation holes are set at 10cm intervals at the bottom of the tank, and a centrifugal fan (air volume 2500m 3 / h) oxygen supply. A removable transparent cover is installed on the top of the system for easy observation and compost turning operations. The system is equipped with temperature sensors (measuring range 0-100°C, accuracy ±0.5°C) to monitor real-time temperatures at the top, middle, and bottom of the compost.

[0075] During dynamic composting, strictly control the compost temperature within the 45-55°C range. This control method involves measuring the temperature every four hours at different locations in the compost pile (three points each on the surface, middle, and bottom layers) using an insertable digital thermometer. If the temperature drops below 45°C, reduce ventilation and cover with plastic film for insulation. If the temperature rises above 55°C, increase ventilation and immediately turn the pile to cool it down.

[0076] The oxygen concentration in the compost pile is measured three times daily using a portable oxygen detector (measuring range 0-25%, accuracy ±0.1%) via a sampling tube pre-buried in the compost pile. Experimental results show that when the oxygen concentration falls below 15%, microbial activity is significantly inhibited. Therefore, when the oxygen concentration is detected below 15%, the compost is immediately turned or ventilation is increased to ensure aerobic conditions. During the dynamic composting stage, the compost is turned once a day to increase the oxygen concentration in the compost pile, ensure smooth aerobic fermentation, and maintain uniform temperature distribution.

[0077] The dynamic composting phase lasts for seven days. During this phase, Trichoderma multiplies rapidly and works synergistically with other microorganisms to accelerate the decomposition of organic matter. The compost temperature reaches its highest point (52°C) on the third day and then gradually stabilizes. During the fermentation process, the material gradually changes from its initial brown color to dark brown, its volume decreases by approximately 20%, and its odor changes from its initial pungent odor to a humic odor.

[0078] 2.4.2 Post-ripening stage

[0079] After dynamic composting is complete, the temperature of the pile gradually drops to 38°C. At this point, the pile is moved to a well-ventilated, semi-open area for post-fermentation. The post-fermentation area has a cement floor, with baffles installed around the perimeter to prevent rainwater intrusion and a simple canopy built on top.

[0080] During the post-ripening phase, the pile is left to ferment for five days, turning it every two days to maintain ventilation. This phase further stabilizes and matures the organic matter, ensuring the stability and safety of the final product.

[0081] At the end of the post-ripening stage, the pile temperature stabilized at 32°C (below 35°C), was dark brown, could be squeezed into a ball but was not sticky, and had no noticeable odor. A sample was taken and the carbon-nitrogen ratio was 17.8 (less than 20), indicating that the material was fully mature and had reached the end of post-ripening.

[0082] 2.5 Function Enhancement and Product Preparation (Corresponding to Step S4)

[0083] 2.5.1 Screening

[0084] After fermentation, the product is screened using a rotary screen with a 1 cm aperture, controlled at 40 rpm (within a range of 30-50 rpm). This process removes coarse impurities and improves product uniformity. Approximately 8% of the product remains unscreened and is returned to the next fermentation batch for reuse.

[0085] 2.5.2 Nutritional Fortification

[0086] To further enhance the fertilizer's nutrient content and functionality, potassium dihydrogen phosphate (2‰ of the fermentation product's mass) and a trace element mixture (ferrous sulfate, zinc sulfate, and copper sulfate, mixed in a 1:1:1 ratio, for a total of 0.5‰ of the fermentation product's mass) were added to the sieved fermentation product. The additions were evenly spread and thoroughly mixed, using a horizontal spiral mixer (15 rpm) for 20 minutes to ensure a uniform mix.

[0087] Adding these nutrients can further supplement phosphorus, potassium and trace elements, improve the comprehensive nutritional value of fertilizers, and meet the multi-element needs of crop growth.

[0088] 2.5.3 Granulation and drying

[0089] After adding the nutritional supplement, the material is granulated using a disc granulator with a rotation speed of 18 rpm (within the range of 15-20 rpm) and an inclination angle of 48° (within the range of 45-50°). During the granulation process, 2% (within the range of 1-2%) of starch is added as a binder to produce granules with a diameter of 2-5 mm. Granulation improves product uniformity and stability, facilitating storage and use.

[0090] The granulated product is then hot-air dried using a hot-air drying device at a temperature of 65°C (within the range of 60-70°C), a wind speed of 1.8 m / s (within the range of 1.5-2.0 m / s), and a drying time of 5 hours (within the range of 4-6 hours) until the moisture content drops to 13% (not greater than 15%). The dried product is then cooled to room temperature and packaged.

[0091] The product is packaged in composite plastic bags, marked with information such as product name, main ingredients, nutrient content, production date, shelf life (12 months at room temperature) and usage instructions.

[0092] 3. Product quality testing

[0093] The quality of the prepared organic compound fertilizer was tested according to relevant standards. The results are as follows: Figure 4 As shown in Table 4.

[0094] The test results show that the pH value of the organic compound fertilizer prepared by the present invention is 6.8 (within the range of 6.5-7.5), the organic matter content is as high as 52.6%, and the nitrogen, phosphorus, and potassium contents are rich, which are 2.86%, 1.53%, and 1.88%, respectively. In terms of heavy metal content, the cadmium content is 0.41 mg / kg (not more than 0.8 mg / kg), and the lead content is 12.5 mg / kg (not more than 25 mg / kg), both of which meet the requirements of the NY525-2021 "Organic Fertilizer" standard. The number of viable Trichoderma reached 3.6×10 6 CFU / g (not less than 1×106 CFU / g), indicating that Trichoderma maintained high activity during the fermentation process. Furthermore, hygiene indicators such as fecal coliform counts and Ascaris egg mortality also met relevant standards, demonstrating that the fermentation process effectively killed pathogenic microorganisms and that the product was safe and reliable.

[0095] 4. Fertilizer efficiency test

[0096] In order to verify the actual effect of the organic compound fertilizer prepared by the present invention, a field test on green sugar beet hearts was carried out.

[0097] 4.1 Test materials and methods

[0098] Test crops: Green sugar beet heart (Brassica rapa chinensis);

[0099] Test location: Test base of a research institute in Baiyun District, Guangzhou City, Guangdong Province (23°16′N, 113°23′E);

[0100] Soil conditions: Sandy loam, pH 6.8, organic matter content 2.1%, total nitrogen 0.15%, total phosphorus 0.08%, total potassium 1.2%;

[0101] Experimental design: Randomized block design, with four treatments, three replicates per treatment, and a plot area of 20 m 2 ;

[0102] The test treatment is as follows:

[0103] Treatment 1 (bio-organic fertilizer treatment): conventional fertilization + burying 80 kg of the bio-organic fertilizer prepared by the present invention per mu as base fertilizer.

[0104] Treatment 2 (inactivated bio-organic fertilizer treatment): conventional fertilization + burying 80 kg of inactivated bio-organic fertilizer (sterilized with high-pressure steam at 121°C for 30 minutes) per mu as base fertilizer.

[0105] Treatment three (conventional control): customary fertilization (local vegetable farmers followed conventional fertilization management and did not apply bio-organic fertilizer).

[0106] Treatment 4 (fine sand control): conventional fertilization + burying 80 kg of fine sand per mu as base fertilizer.

[0107] Before transplanting, all treatments applied 120 kg of commercial organic fertilizer (organic matter ≥30%, N+P2O5+K2O ≥4.0%) per mu as base fertilizer. One week later, 10 kg of compound fertilizer (15-15-15) per mu was applied as topdressing. During the entire growth period, the plants were washed 37 times and sprayed with pesticides twice (this was standard local practice).

[0108] 4.2 Measurement indicators and methods

[0109] Fifteen plants were randomly selected from each plot to measure the following indicators:

[0110] Plant height: measured with a ruler, with an accuracy of 0.1 cm;

[0111] Stem diameter: measured using a vernier caliper with an accuracy of 0.01 mm;

[0112] Taproot length: measured with a ruler, accuracy of 0.1 cm;

[0113] Single plant weight: weighed using an electronic balance with an accuracy of 0.1g;

[0114] Plot yield: Calculated by harvesting and weighing the cauliflower in the entire plot.

[0115] 4.3 Test results

[0116] The test results are as follows Figure 1 、 Figure 2 、 Figure 3 As shown in Table 1, Table 2 and Table 3.

[0117] 4.4 Results Analysis

[0118] As shown in Tables 1 and 3, compared with the other treatments, treatment 1 (bio-organic fertilizer treatment) significantly increased the plant height, stem diameter, taproot length, and plant weight of Chinese cabbage. The plant height in treatment 1 was 43.8 cm, 2.2 cm, 3.4 cm, and 3.0 cm higher than treatments 2, 3, and 4, respectively. The stem diameter was 9.26 mm, 0.73 mm, 1.01 mm, and 0.88 mm higher than treatments 2, 3, and 4, respectively. The taproot length was 9.42 cm, 0.71 cm, 1.12 cm, and 0.96 cm longer than treatments 2, 3, and 4, respectively. The plant weight was 156.8 g, 9.2 g, 14.5 g, and 12.7 g heavier than treatments 2, 3, and 4, respectively.

[0119] The yield data in Table 2 show that the plot and per mu yield of treatment 1 (bio-organic fertilizer treatment) were the highest, at 41.3 kg / 20 m 2 and 1376.7kg / 667m 2 The yield per mu increased by 5.98%, 11.19% and 10.58% compared with treatment 2, treatment 3 and treatment 4 respectively.

[0120] It is particularly noteworthy that treatment 1 (bio-organic fertilizer) has a better growth-promoting effect than treatment 2 (inactivated bio-organic fertilizer), which proves that live Trichoderma plays an important role in promoting crop growth, not just providing nutrients. Trichoderma in bio-organic fertilizer may promote crop growth through the following mechanisms: (1) secreting plant growth regulators such as auxins and gibberellins; (2) dissolving insoluble elements such as phosphorus and potassium in the soil to improve nutrient availability; (3) producing antibiotics and competing to inhibit the growth of soil-borne pathogens; and (4) inducing systemic resistance in plants to enhance their resistance to adverse environments.

[0121] By performing variance analysis on the experimental data, the differences among the treatments reached a significant level (P<0.05), indicating that the bio-organic fertilizer prepared by the present invention has a statistically significant effect on promoting the growth and yield of Chinese cabbage.

[0122] 5. Technical Effect

[0123] It can be seen from the above examples that the black soldier fly excrement-Trichoderma organic compound fertilizer prepared by the present invention has the following technical effects:

[0124] (1) Functional synergy: The combination of black soldier fly excrement and Trichoderma achieves a synergistic effect in nutrient supply and disease control. Black soldier fly excrement provides rich organic matter and nutrients, while Trichoderma improves the efficiency of organic matter decomposition and gives the fertilizer the function of biological control of soil-borne diseases. This functional synergistic effect enables the organic compound fertilizer of the present invention to provide comprehensive and balanced nutrition for crops and enhance their disease resistance, effectively solving the problem of the single function of existing insect excrement fertilizers.

[0125] (2) Process Optimization: This invention uses a fermentation process that combines dynamic composting with a post-ripening stage, shortening the fermentation cycle to 12 days (7 days for dynamic composting and 5 days for post-ripening), significantly improving production efficiency. The closed dynamic composting system can precisely control fermentation environmental parameters such as temperature and oxygen, ensuring the dominant growth of beneficial microorganisms such as Trichoderma, while also reducing odor emissions and lowering environmental impact.

[0126] (3) Product Safety: The organic compound fertilizer prepared by the present invention uses black soldier fly feces as its primary raw material. After undergoing a high-temperature fermentation process at 45-55°C, it effectively kills pathogens and parasite eggs, achieving a 99.0% mortality rate for roundworm eggs. The heavy metal content in the product is well below the national organic fertilizer standard limit, with a cadmium content of only 0.41 mg / kg (standard limit 0.8 mg / kg) and a lead content of 12.5 mg / kg (standard limit 25 mg / kg). This product is safe, reliable, and environmentally friendly.

[0127] (4) Significant fertilizer efficiency: Field test results show that the bio-organic fertilizer prepared by the present invention can significantly promote the growth and development of green sugar beet hearts and increase yield. Compared with the conventional control, the yield per mu increased by 11.19%; compared with the inactivated bio-organic fertilizer, the yield per mu increased by 5.98%, demonstrating the important role of live Trichoderma in promoting crop growth and improving fertilizer efficiency.

[0128] (5) Sustainability: This invention utilizes black soldier fly bioconversion technology to treat organic waste, converting it into high-value organic fertilizer raw materials, thus achieving resource recycling. Furthermore, the introduction of Trichoderma reduces the need for chemical pesticides, aligning with the development of green agriculture and providing significant ecological and social benefits.

[0129] In summary, the method for preparing organic compound fertilizer by combining black soldier fly feces with Trichoderma provided in this embodiment has the characteristics of reasonable process, simple operation, low cost, and significant effect. It can be industrialized and has broad application prospects.

[0130] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing organic compound fertilizer by combining black soldier fly excrement with Trichoderma, characterized in that: The following steps are involved: S1, pre-treating black soldier fly excrement to obtain pre-treated black soldier fly excrement; S2, mixing the pretreated black soldier fly excrement with auxiliary materials, and adjusting the moisture content of the materials; S3, inoculating Trichoderma into the mixed material for aerobic fermentation; S4, screening, nutritionally enriching and granulating the fermentation product to obtain an organic compound fertilizer; Among them, the black soldier fly feces provides organic matter and nutrients, the Trichoderma promotes the decomposition of organic matter during the fermentation process and gives the organic compound fertilizer a biological control function, and the synergistic effect of black soldier fly feces and Trichoderma realizes the nutrient supply and disease prevention and control functions of the organic compound fertilizer.

2. The method for preparing organic compound fertilizer by combining black soldier fly excrement with Trichoderma according to claim 1, characterized in that: In step S1, the pretreatment of the black soldier fly excrement includes a drying treatment, wherein the drying treatment is selected from natural air drying at an ambient temperature of 25-30° C. for 2-3 days or low-temperature drying in an oven at 50-60° C. for 8-12 hours, until the moisture content of the black soldier fly excrement is no more than 20%; When the initial moisture content of the black soldier fly feces is high, it should be subjected to a centrifugal dehydration process at 3000 rpm for 10 minutes or a mechanical filter press pre-dehydration process at 0.5-0.8 MPa before drying. The dosage of the black soldier fly excrement is 40%-60% of the total amount of the formula.

3. The method for preparing organic compound fertilizer by combining black soldier fly excrement with Trichoderma according to claim 1, characterized in that: In step S2, the auxiliary material is selected from straw powder, pine sawdust or a combination thereof, and the amount of the auxiliary material added is 30%-50% of the total amount of the formula; The particle size of the straw powder is no more than 2 cm, the carbon-nitrogen ratio of the pine sawdust is 25-30, and the particle diameter is 0.5-2 cm; and the moisture content of the auxiliary material before use is lower than 15%.

4. The method for preparing organic compound fertilizer by combining black soldier fly excrement with Trichoderma according to claim 3, characterized in that: In step S2, the pretreated black soldier fly feces and the auxiliary material are mixed in a ratio of 6:4; The mixing is carried out using a horizontal spiral mixer or a special compost turning machine with a rotation speed of 15-20 rpm; The water content of the mixed material is adjusted to 45-55% by evenly spraying an appropriate amount of water through a sprayer.

5. The method for preparing organic compound fertilizer by combining black soldier fly excrement with Trichoderma according to claim 1, characterized in that: In step S3, the Trichoderma is selected from Trichoderma harzianum or Trichoderma viride, and the spore concentration is not less than 1×10 8 CFU / g; The inoculation amount of the Trichoderma is 1%-3% of the total amount of the material; The inoculation method is selected from the following: evenly spreading dry powder or spraying it after preparing a suspension mixed with water in a ratio of 1:10; Avoid temperatures above 35°C or direct sunlight during the inoculation process.

6. The method for preparing organic compound fertilizer by combining black soldier fly excrement with Trichoderma according to claim 5, characterized in that: In step S3, the aerobic fermentation includes a dynamic composting stage and a post-ripening stage; The dynamic composting stage is carried out using a closed dynamic composting system, the compost temperature is controlled at 45-55° C., the oxygen concentration is not less than 15%, the compost is turned once a day, and the dynamic composting stage lasts for 7 days.

7. The method for preparing organic compound fertilizer by combining black soldier fly excrement with Trichoderma according to claim 6, characterized in that: During the post-ripening stage, the pile is transferred to a well-ventilated semi-open area for post-ripening fermentation and allowed to stand for 5 days, during which the pile is turned over every 2 days; The criteria for judging the end of the after-ripening stage are: the pile temperature is stable below 35° C., the pile is dark brown, there is no obvious odor, the pile material structure is loose, it can be squeezed into a ball but is not sticky, and the carbon-nitrogen ratio is less than 20.

8. The method for preparing organic compound fertilizer by combining black soldier fly excrement with Trichoderma according to claim 1, characterized in that: In step S4, the screening is performed using a rotary screening machine or a vibrating screen with a pore size of 1 cm, and the screening speed is controlled at 30-50 rpm; The nutritional fortification includes adding potassium dihydrogen phosphate in an amount of 2‰ of the mass of the fermentation product and trace elements in an amount of 0.5‰ of the mass of the fermentation product to the fermentation product after screening, and the trace elements are a mixture of ferrous sulfate, zinc sulfate, and copper sulfate in a ratio of 1:1:

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9. The method for preparing organic compound fertilizer by combining black soldier fly excrement with Trichoderma according to claim 8, characterized in that: In step S4, the granulation is carried out using a disc granulator with a rotation speed of 15-20 rpm and an inclination angle of 45-50° or an extrusion granulator with a die hole diameter of 2-4 mm, and 1-2% starch or molasses is added as a binder during the granulation process to produce granules with a diameter of 2-5 mm; The granulated product is dried, and the drying process is selected from natural airing with a thickness of no more than 5 cm, turning 2-3 times a day, and drying for 2-3 days under sunny conditions, or hot air drying at a temperature of 60-70° C., a wind speed of 1.5-2.0 m / s, and a drying time of 4-6 hours, until the moisture content is no more than 15%.

10. The method for preparing organic compound fertilizer by combining black soldier fly excrement with Trichoderma according to claim 1, characterized in that: The pH value of the organic compound fertilizer is 6.5-7.5; The heavy metal content of the organic compound fertilizer is: cadmium content is not more than 0.8 mg / kg, lead content is not more than 25 mg / kg; The number of viable bacteria of Trichoderma in the organic compound fertilizer is not less than 1×10 6 CFU / g.

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