Walking through the fields, few people consider how those nitrogen, phosphorus, and potassium granules that nourish crops are actually manufactured. Their creation is not merely a chemical reaction, but an industrial journey of shaping form.
In modern fertilizer plants, production often begins with a series of precise physical mixtures. For blended fertilizers requiring flexible formulations, bulk blending fertilizer machines play a crucial role. Like a giant mixing bowl, it gathers bulk nitrogen, phosphorus, and potassium raw materials from different sources according to a pre-set “recipe.” Amidst the roar of the machines, granules of various colors are efficiently and uniformly mixed, ensuring that every scoop of the final product contains a completely consistent nutrient ratio, laying the foundation for precision agriculture.
However, powder or physically mixed granules are sometimes not in the optimal form. To obtain fertilizers with higher strength and easier storage and application, fertilizer compaction machines demonstrate their power. Under powerful extrusion, they shape loose powder into uniformly sized, dense granules.
For large-scale continuous production, the rotary drum granulator paints a dynamic picture. Inside this slowly rotating giant cylinder, powdery raw materials are slightly moistened, tumbling, colliding, and agglomerating as the cylinder rotates, gradually growing into uniform, round granules.
From uniform mixing to powerful pressing and shaping, and then to rolling and agglomeration, the production of NPK fertilizer is a skillful shaping of nutrients by industrial forces. Ultimately, these granules of various shapes carry the same mission: to be integrated into the soil.
In the field of bio-organic fertilizer production, the coordinated operation of bio-organic fertilizer equipment is crucial for ensuring production capacity and quality. The fertilizer granulator, as a core piece of equipment, directly determines the granule formation effect. The fertilizer granules compaction machine, with its mature fertilizer granules compaction technology, has become one of the most favored granulation devices in bio-organic fertilizer production lines.
The fertilizer granules compaction machine is an important type of fertilizer granulator, and its core advantage stems from advanced fertilizer granules compaction technology. This technology uses mechanical extrusion to compress and shape pre-treated organic fertilizer raw materials. It requires minimal addition of binders, preserving the organic matter and nutrients in the raw materials while improving the granule formation rate. The resulting granules have moderate hardness, are not easily broken, and meet the quality requirements of bio-organic fertilizers.
In a complete bio-organic fertilizer production line, the fertilizer compaction machine works seamlessly with other bio-organic fertilizer equipment. After fermentation, crushing, and screening, the raw materials are transported to the fertilizer compaction machine by conveying equipment, where granulation is completed through extrusion technology. Subsequent processing by cooling and screening equipment ultimately produces qualified bio-organic fertilizer products.
Compared to other granulation methods, fertilizer granules compaction machines using fertilizer granules compaction technology are more adaptable and can process a variety of organic fertilizer raw materials, including fermented materials such as poultry and livestock manure and crop straw, achieving efficient granulation. It is not only a high-quality fertilizer granulator but also an important support for achieving large-scale and standardized production in bio-organic fertilizer production lines.
Introduction: When Hard Materials Meet Powerful Crushing
In industries such as fertilizer production, mineral processing, and building material preparation, there is often a need to crush medium-hard to hard materials like coal lumps, limestone, shale, or dried fertilizer raw materials into uniform fine particles. Traditional hammer or jaw crushers may face issues of insufficient efficiency or rapid wear when dealing with these materials. The chain crusher, with its unique chain-hammer composite design, has become the ideal choice for handling such materials. It holds an important position in the field of industrial crushing due to its powerful impact force and excellent wear resistance.
I. Core Design: The Crushing Revolution Brought by Chains
The core innovation of the chain crusher lies in its rotor assembly. Instead of using fixed hammers, multiple high-strength alloy steel chains are suspended from the rotor, with wear-resistant hammer heads (chain heads) attached to their ends. When the rotor rotates at high speed driven by a motor (chain head peripheral speed can reach 28-78 m/s), these freely swinging chains and hammer heads act like countless high-speed whipping steel lashes, delivering omnidirectional and violent impacts to the material entering the crushing chamber.
This design offers multiple advantages: First, the freely swinging chains can better “wrap around” and strike irregularly shaped materials. Second, when encountering unbreakable foreign objects, the chains can yield to a certain extent, reducing impact on the main shaft and protecting the equipment. Finally, the combined effect of chain impact, collision between material and the chamber’s liner plates, and inter-particle friction creates an efficient composite crushing mechanism.
II. Working Principle: A Trilogy for Fine Crushing
The workflow of a chain crusher is clear and efficient:
Feeding and Primary Crushing:Material enters the sturdy housing through the feed inlet and immediately encounters the first wave of impact from the high-speed rotating chain hammers. Large lumps of material are rapidly fractured.
Multiple Crushing and Grinding:The material being crushed is repeatedly tossed within the chamber, subjected to continuous impacts from chains at different angles. Simultaneously, smaller particles move at high speed inside the chamber, colliding violently and grinding against the liner plates and other particles, being further refined. This process combines impact crushing with some grinding action.
Sieving and Qualified Discharge:Material refined to a certain degree is pushed towards the bottom screen by airflow and centrifugal force. Only particles smaller than the screen apertures pass through and are discharged from the outlet. Oversized particles are retained by the screen and continue to be crushed inside the chamber until they meet the size requirement.
III. Structural Types: Adapting to Different Scale Needs
To meet diverse production needs, chain crushers mainly come in two structures:
Single-Motor Vertical Structure: Compact design with a small footprint, featuring a vertically arranged rotor. Suitable for small to medium-scale production lines with limited space or applications with lower throughput requirements. A common choice for fertilizer plants and small building material factories.
Dual-Motor Horizontal Structure: Features two horizontally arranged rotors, each independently driven by a motor, providing powerful crushing capacity. This design is typically used for large-scale industrial production, such as in large cement plants, mining operations, or large compound fertilizer production lines, capable of achieving throughputs of tens or even hundreds of tons per hour.
IV. Outstanding Advantages: Why is it Highly Favored?
Chain crushers demonstrate significant advantages across multiple dimensions:
High-Efficiency Crushing Capacity:High-speed impacts can quickly disintegrate hard materials, resulting in high production efficiency.
Wide Material Adaptability:It can not only process hard materials such as coal and limestone, but also has a good crushing effect on fertilizer raw materials and clay containing a certain amount of moisture or viscosity.
Excellent Product Size Control:By changing the sieves with different mesh sizes, the particle size of the final product can be easily adjusted to meet the precise requirements of downstream processes.
Robust Durability and Easy Maintenance:Key components like chains, chain heads, and liner plates are made of wear-resistant materials for long service life. The equipment is designed with large access doors, making the replacement of wear parts and routine maintenance very convenient.
Good Overload Protection:The flexible connection characteristics of the chain provide a certain degree of cushioning when encountering unbreakable foreign objects such as metal fragments, thereby reducing the risk of sudden equipment failure.
V. Typical Applications: Empowering Multiple Industries
The chain crusher is a versatile key piece of equipment in multiple industries:
Fertilizer Industry: Used for crushing raw materials like phosphate rock and potash feldspar, or for crushing and screening dried compound fertilizer lumps.
Building Materials Industry: Crushing raw materials like limestone, shale, and gypsum for cement or brick production.
Mining and Energy: Used for primary crushing of coal or other medium-hardness ores.
Chemical Industry: Processing certain caked chemical raw materials or intermediate products.
From Crushing to Granulation: An Integrated Production Workflow
Efficient material reduction, such as that achieved by a chain crusher, is a critical pre-processing step in modern fertilizer manufacturing, serving both npk fertilizer production line and organic fertilizer production line systems. The uniformly crushed powder is then precisely formulated, often using a npk blending machine for compound fertilizers, before entering the core fertilizer granulation processes. Advanced fertilizer granulation technology offers diverse pathways: dry granulation processes utilize equipment like the double roller press granulator in a roller press granulator production line, while wet methods might employ a disc granulator for shaping in a disc granulation production line.
For organic production, the chain often starts with a windrow composting machine for biodegradation before granulation. The choice of fertilizer processing machine—be it a disc granulator machine, roller press, or other fertilizer granulator—is determined by the material properties and final product specifications. Whether configured for a high-volume npk fertilizer line or a specialized bio organic fertilizer production line, this integration of pre-processing, precise blending, and selective granulation ensures the efficient production of high-quality, consistent fertilizers that meet the specific demands of global agriculture.
Conclusion
Chain crushers, with their unique crushing principle, strong adaptability, and exceptional durability, have successfully solved the problem of efficiently crushing medium-hard materials in the industrial field. They transform the initial impact force into controllable, refined crushing force, becoming an indispensable bridge connecting raw material pretreatment and subsequent deep processing stages. With the continuous advancement of materials science and manufacturing technology, future chain crushers will develop towards higher energy efficiency, intelligence, and lower wear, continuing to provide reliable core equipment support for global industrial production and resource processing.
Against the backdrop of global urbanization and intensive agricultural development, the generation of organic waste is increasing exponentially. From urban food waste to livestock manure, from post-harvest crop residues to food processing by-products, these seemingly useless materials can become a source of environmental pollution if improperly handled; if managed correctly, they can be transformed into “black gold” that nourishes the soil and promotes crop growth. Fermentation technology is the key to achieving this magical transformation. It is not only an ancient agricultural wisdom but also a core technology in modern circular agriculture and sustainable environmental management. This article will systematically introduce how to convert various organic wastes into high-quality fertilizer resources through fermentation, clarify common misconceptions about fertilizers, and provide a practical guide for home gardening enthusiasts, small-scale farmers, and agricultural practitioners alike.
Part I: The Core of Organic Waste Fermentation – Aerobic Composting
Aerobic composting is a process that utilizes naturally occurring aerobic microorganisms, under artificially created suitable conditions, to rapidly decompose organic matter into stable, harmless, and humus-rich material. This process mimics and accelerates the natural material cycle, and its success depends on the precise control of several key elements.
Step 1: Careful Raw Material Preparation
Successful fermentation begins with proper raw material pretreatment. First, strict sorting is essential to remove non-biodegradable impurities such as plastics, metals, and glass, which cannot be decomposed by microorganisms and will contaminate the final product. Second, physical treatment of the raw materials is necessary. For coarse fibrous materials like straw, sawdust, and yard trimmings, shredding them to a size of 2-5 cm is crucial, as it greatly increases their surface area, facilitating microbial attachment and decomposition. Finally, and most importantly, adjusting the carbon-to-nitrogen ratio and moisture content of the mixture is key. The ideal carbon-to-nitrogen ratio is between 25:1 and 30:1. Common “green” materials (such as fresh kitchen waste, livestock manure) are rich in nitrogen but low in carbon, while “brown” materials (such as dry leaves, wood chips, straw) are rich in carbon. Mixing the two in proportion (e.g., 3 parts chicken manure to 1 part shredded straw) is the foundation for efficient fermentation. Simultaneously, the moisture content of the material should be adjusted to 55%-60%, with a texture that feels “forms a ball when squeezed but breaks apart easily when dropped,” providing an ideal moisture environment for microbial activity.
Step 2: Scientific Pile Construction and Management
Building a suitable pile with the mixed materials is the core step. The recommended pile dimensions are: base width of 1.5-2 meters, height of 1.2-1.5 meters, and length adjusted according to the amount of material, with the overall shape being trapezoidal or arched. This structure ensures sufficient volume inside the pile for heat retention while allowing oxygen to penetrate from the outside into the core area. To accelerate the start of fermentation, microbial inoculants (such as EM bacteria, commercial compost starters, or a small amount of mature compost) can be added.
The fermentation process typically involves three stages, requiring dynamic management: Mesophilic Phase: Within 1-3 days of starting the compost, mesophilic microorganisms multiply rapidly, decomposing simple sugars and starches, and the pile temperature quickly rises to around 50°C. The pile should be kept loose during this phase. Thermophilic Phase: As the temperature rises to 55-65°C, thermophilic microorganisms become dominant. This stage needs to be maintained for at least 5-7 days. It effectively kills pathogens, insect eggs, and weed seeds, which is key to the sanitization of the compost. During this period, thorough turning every 2-3 days is essential to replenish oxygen, dissipate heat, and expel harmful gases (like ammonia), preventing the pile from becoming anaerobic and producing foul odors due to lack of oxygen. Cooling and Maturation Phase: When easily degradable organic matter is mostly consumed, the pile temperature gradually drops below 40°C, entering a maturation phase lasting 20-30 days. At this stage, microorganisms like actinomycetes begin their work, synthesizing stable humus. The pile volume significantly reduces, the color turns dark brown or black, the texture becomes loose, and it emits an earthy fragrance. Turning frequency can be reduced to once every 5-7 days.
Step 3: Accurate Determination of Maturity
Whether the fermentation product is fully mature directly affects its safety and effectiveness. Judgment criteria include: uniform dark brown appearance, loose texture without clumps, and no pungent odors like ammonia. More precise indicators include: moisture content reduced to 25%-30%, and pH stabilized in the near-neutral range of 6.5-7.5. A simple and effective biological test is the “Seed Germination Rate Test”: soak a small amount of mature material in water, filter it, and use the filtrate to water seeds that germinate easily, such as radish or pak choi. If the germination rate exceeds 80% and root growth is normal, it indicates complete maturity and no phytotoxicity.
Part II: Clarifying Concepts: Amino Acid Fertilizer vs. Organic Fertilizer
In the field of fertilizers, concepts are often confused. Amino acid fertilizers and organic fertilizers are two different products serving different agricultural goals.
Organic fertilizer, as described above, is a product made from organic waste (such as manure, straw) through fermentation and maturation. Its core value lies in adding stable organic matter and humus to the soil, improving soil physical structure (e.g., increasing porosity, water retention), fostering beneficial microbial communities, and slowly and persistently releasing nutrients over the long term. It is the “foundational building material” for constructing a healthy, vibrant soil ecosystem.
Amino acid fertilizer is typically a solution of free amino acids extracted from raw materials like animal hair or plant protein through chemical or enzymatic hydrolysis processes, often chelated with trace elements. It falls under the category of functional fertilizers or organic water-soluble fertilizers. Its mechanism of action is to allow plant leaves or roots to directly absorb small-molecule amino acids, which quickly participate in plant metabolism, promoting photosynthesis, enhancing stress resistance (e.g., cold, drought), improving fruit set rates, etc. It is more like an efficient “plant nutrient infusion” rather than a soil amendment.
Therefore, the two are not substitutes but complementary. In agricultural production, using organic fertilizer as a base fertilizer for long-term soil improvement, combined with amino acid fertilizer as a foliar spray or fertigation for rapid nutrient supplementation during critical crop growth stages, can achieve the best results of “addressing both symptoms and root causes.”
Part III: Special Focus: The Correct Use of Chicken Manure
Chicken manure is an organic resource with extremely high nutrient content, but its use must follow an iron rule: it must be fully matured before application.
The hazards of uncomposted chicken manure are significant: It carries a large number of pathogens (e.g., E. coli, nematodes) and weed seeds. Direct application can cause severe crop diseases. In the soil, uncomposted chicken manure undergoes intense secondary fermentation, generating high temperatures and large amounts of ammonia, leading to “root burn” that damages plant roots and disrupts the soil microecological balance.
Composted chicken manure, however, is a treasure: After standardized aerobic composting fermentation, the aforementioned hazards are completely eliminated. Mature chicken manure becomes a high-quality organic fertilizer with comprehensive nutrients (nitrogen, phosphorus, potassium, and various secondary and trace elements), long-lasting fertilizer efficiency, and the ability to significantly increase soil organic matter and improve aggregate structure. It is suitable for almost all types of crops and is an ideal fertilizer source for producing green and organic agricultural products.
Scaling Up Organic Fertilizer Production: From Principle to Factory
The scientific principles of organic fertilizer fermentation for small-scale composting are the foundation for large-scale industrial production. In a modern organic fertilizer factory, this process is systematized into a complete organic fertilizer production line. Efficient, large-scale organic fertilizer manufacturing employs advanced fermentation composting turning technology to optimize the aerobic decomposition process. Following complete maturation, the stabilized compost proceeds to the granulation stage, where it is shaped into a marketable product.
This final step utilizes specialized fertilizer granulator equipment. Innovations like the new type two in one organic fertilizer granulator combine mixing and pelletizing for efficiency. These granulators, whether standard models or part of abio organic fertilizer production line that includes microbial inoculation, are central to transforming bulk compost into uniform pellets. The entire industrial workflow thus scales up the core composting principles, enabling the efficient, consistent production of high-quality organic fertilizers that support sustainable agriculture by improving soil health and recycling valuable nutrients from waste.
Conclusion
Mastering the fermentation technology for organic waste is the process of transforming waste management from a cost center to a value-creating activity. It connects environmental governance with agricultural production, shifting from a linear consumption model to a circular regeneration model. Whether it’s a small compost bin at home or a large-scale fermentation facility on a farm, the principles are the same. Through scientific methods, we can not only reduce waste and protect the environment but also produce valuable resources that nourish the land and cultivate healthy crops, contributing to sustainable agriculture and living.
Introduction: Importance of Understanding Fertilizer Behavior
In modern agriculture, the selection and application methods of fertilizer granules directly affect crop yield and soil health. Understanding fertilizer dissolution time and its impact on soil structure is a crucial step toward sustainable agriculture. This article scientifically analyzes the dissolution characteristics of different types of fertilizer granules and explores their relationship with soil compaction, providing practical guidance for growers worldwide.
I. Dissolution Time of Fertilizer Granules
The dissolution time of fertilizer granules depends on their chemical composition, physical structure, and manufacturing process. Understanding these differences helps farmers make informed choices based on crop needs and growth stages.
1. Fast-acting Fertilizer Granules
Fast-acting fertilizers typically refer to conventional chemical compound fertilizers, such as standard NPK granular fertilizers. These granules are made from water-soluble compounds with relatively loose structures that quickly break down upon contact with water. Under suitable soil moisture conditions, such fertilizers usually dissolve completely within 1-3 days, allowing nutrients to be immediately absorbed by crop roots. This rapid-release characteristic makes them particularly suitable for quickly supplementing nutrients during critical crop growth stages, but dosage must be carefully controlled to avoid root damage or nutrient loss due to excessive concentration.
2. Slow/Controlled-release Fertilizer Granules
Slow-release and controlled-release fertilizers regulate nutrient release rates through special coating technologies, representing significant advancements in fertilizer technology. Slow-release fertilizers typically use polymer or sulfur coatings, with dissolution cycles of approximately 20-60 days, where nutrients are gradually released as the coating degrades. Controlled-release fertilizers employ more precise coating technologies, allowing nutrient release cycles to be accurately designed for 3-6 months or even longer by controlling membrane thickness and composition. Such fertilizers significantly reduce fertilization frequency and improve nutrient utilization efficiency, making them particularly suitable for long-growth-period crops or areas where frequent fertilization is difficult.
3. Organic Fertilizer Granules
The “dissolution” of organic fertilizer granules is essentially a microbial decomposition process. Organic fertilizer granules made from composted animal manure or plant residues require gradual decomposition by soil microorganisms to release nutrients. This process typically takes 2-6 months, depending on soil temperature, moisture, and microbial activity. During decomposition, organic fertilizers not only provide nutrients but also improve soil biodiversity, though their nutrient release rate and concentration are relatively low, usually requiring combination with other fertilizers.
II. Relationship Between Fertilizers and Soil Compaction
Soil compaction refers to the destruction of soil structure, reduction of pores, and increased hardness. Fertilizers themselves are not the direct cause of compaction, but improper fertilization methods can exacerbate this problem.
1. Situations That May Cause Soil Compaction
Long-term exclusive use of certain chemical fertilizers is one of the main causes of soil compaction. For example, excessive application of physiologically acidic fertilizers such as ammonium chloride and ammonium sulfate can lower soil pH, destroy soil aggregate structure, and reduce soil permeability and water retention capacity. Additionally, using incompletely composted organic fertilizers can also cause problems, as these fertilizers continue to ferment in the soil, consuming oxygen and producing organic acids that inhibit beneficial microbial activity, indirectly leading to soil structure deterioration. Failure to perform proper deep plowing or irrigation after fertilization can cause fertilizer salts to accumulate in surface soil, squeezing soil pores and increasing compaction risk.
2. Situations Unlikely to Cause Soil Compaction
Scientific fertilization can completely avoid or minimize soil compaction risk. Combining well-composted organic fertilizers with chemical fertilizers is one of the most effective strategies, as organic matter promotes soil aggregate formation and improves soil buffering capacity. Due to their gradual nutrient release, slow-release and controlled-release fertilizers do not cause sharp increases in soil salt concentration, exerting far less pressure on soil structure than fast-acting chemical fertilizers. Adopting advanced techniques such as fertigation and deep fertilization ensures even fertilizer distribution, avoids surface accumulation, and further reduces compaction potential.
III. Globally Applicable Fertilization Recommendations
Based on the above analysis, we offer the following recommendations for global growers: First, conduct soil tests to understand current soil conditions and crop needs; second, select fertilizers with appropriate release characteristics according to crop growth cycles (fast-acting fertilizers for short-growth-period crops, slow-release fertilizers for perennial crops); third, establish an organic-inorganic combined fertilization system, applying high-quality organic fertilizer at least once annually to improve soil; fourth, adopt scientific fertilization methods such as deep placement and drip irrigation to improve fertilizer utilization efficiency; finally, regularly monitor soil conditions and adjust fertilization strategies accordingly.
From Industrial Process to Field Performance: The Journey of a Fertilizer Granule
The diverse dissolution profiles and physical properties of fertilizer granules are a direct result of advanced fertilizer granulation technology employed during the manufacturing of npk fertilizer. The choice of process is fundamental: dry granulation processes utilize the principle of fertilizer granules compaction within a fertilizer compaction machine to create dense, slow-release pellets. In contrast, wet granulation methods, such as those using a rotary drum granulator, produce granules with different structural characteristics. The entire npk manufacturing process integrates this core shaping technology into a complete system of fertilizer manufacturing plant equipment, which may include a roller press granulator production line for compaction or a disc granulation production line for wet shaping.
For organic fertilizers, the production chain starts differently, often with decomposition aided by equipment like a windrow composting machine, before the material is processed by specialized fertilizer processing machine equipment. Regardless of the pathway, modern fertilizer production machine systems are engineered to produce granules with specific physical properties—such as hardness, density, and porosity—that directly influence their dissolution rate and interaction with soil. This sophisticated engineering ensures that the final product delivered to the field, whether a compacted NPK granule or an organically derived pellet, performs as intended: delivering nutrients efficiently while minimizing negative impacts on soil structure, thereby supporting sustainable crop production and soil health management.
Conclusion
The dissolution time of fertilizer granules ranges from days for fast-acting fertilizers to months for organic fertilizers, and selection should be based on crop needs and growth stages. Soil compaction is not an inevitable consequence of fertilizer use but rather the result of improper fertilization methods. By rationally combining fertilizer types and adopting scientific application methods, we can not only meet crop nutritional requirements but also improve soil health, achieving sustainable agricultural development. With advancements in fertilizer technology and the spread of agricultural knowledge, global farmers will have more tools and methods to balance production needs with environmental protection.
Upon entering a composting site, the large wheel compost turner often immediately catches the eye. Moving slowly and steadily, its massive rotating disc churns and scatters the material layer by layer, like a tireless dancer endlessly circling the composting stage.
The unique feature of this machine lies in its processing method—it completes the turning and scattering operation without needing to transfer the material elsewhere. As the disc rotates, air is naturally delivered deep into the material, and moisture evaporates evenly, creating an ideal living environment for microorganisms. This is a crucial step in the composting process, directly affecting the quality of subsequent granulation.
Speaking of granulation, different processes have their advantages and disadvantages. In organic fertilizer production, flat die pelleting machines are favored for their compact structure, suitable for small to medium-sized production lines. Ring die pelleting machines, on the other hand, occupy a place in large-scale production due to their stable granule quality and high output. For processing fertilizers with special formulations, the unique tumbling action of the rotary drum granulator can achieve even better granulation results.
These granulation devices each have their own strengths, but they all rely on thorough fermentation treatment in the early stages. The large wheel compost turner plays a crucial role in this preparation stage, and its uniform mixing lays a solid foundation for subsequent processes.
In the selection of raw materials for bio-organic fertilizer production lines, cow dung is one of the core raw materials, and its quality directly determines the granulation effect and product quality of the organic fertilizer. Not all cow dung is suitable for granulation; strict selection from multiple dimensions is necessary to ensure the smooth operation of the granulation process in the bio-organic fertilizer production line and that the product meets the standards.
First, prioritize fresh cow dung from healthy beef or dairy cattle. The manure of healthy cows is free from pathogens and insect eggs, and the organic matter, nitrogen, phosphorus, and potassium nutrients are fully preserved. It is the core source of nutrients for bio-organic fertilizer and lays a solid foundation for subsequent stages of the bio-organic fertilizer production line. Avoid manure from sick cows or cows undergoing medication. This type of cow dung may contain residual pathogens or drug components, which not only affects the safety of the granulated organic fertilizer but may also cause abnormalities in the fermentation process of the bio-organic fertilizer equipment.
Secondly, control the degree of cow dung decomposition. Uncomposted raw cow dung should never be directly granulated. Raw cow dung will continue to ferment and heat up after granulation, easily leading to granule expansion and cracking, and may burn crop roots when applied. It is recommended to use fully composted cow dung, which is dark brown, odorless, and has a loose texture. The organic matter has been fully decomposed, which not only facilitates the formation of uniform granules but also improves the stability of the organic fertilizer’s effectiveness.
In addition, strictly control the impurity content of the cow dung. Cow dung used for granulation needs to be cleaned of impurities such as stones, plastics, metals, and weed roots beforehand to prevent damage to the granulation components of the bio-organic fertilizer equipment, affecting the granule formation rate and uniformity, and slowing down the overall efficiency of the bio-organic fertilizer production line. The moisture content should also be adjusted to 25%-35%. Too high a moisture content can cause sticking and clumping, leading to blockages in the bio-organic fertilizer equipment, while too low a moisture content makes granulation difficult. This can be adjusted by drying or adding auxiliary materials.
During the operation of a fertilizer mixer machine, the state and handling of the materials directly determine the mixing effect, equipment lifespan, and ultimately the quality of the final fertilizer product. Especially for organic and compound fertilizer production, controlling material-related considerations is a core prerequisite for ensuring a smooth overall production process of the bio-organic fertilizer equipment.
Material particle size uniformity must be prioritized. Materials fed into the mixer should be crushed and screened beforehand to avoid excessive mixing of coarse and fine particles—large particles tend to settle at the bottom of the equipment and cannot be fully mixed, while excessively fine powder may generate dust due to the mixing airflow and can easily lead to localized clumping. It is recommended to control the material particle size within a uniform range based on mixing requirements.
Material moisture content must be precisely controlled. The appropriate moisture content varies for different fertilizer materials, but generally needs to be controlled between 20% and 30%: excessively high moisture content can cause materials to stick to the mixing blades and machine walls, affecting mixing uniformity and potentially increasing equipment load; excessively low moisture content results in excessive material fluidity, making it difficult to achieve a stable mixing state, and may even cause dust pollution.
Mixing of impurities and incompatible materials is strictly prohibited. Materials must be thoroughly cleaned before feeding to remove hard impurities such as stones, metal fragments, and plastics; at the same time, mixing of materials with conflicting properties should be avoided to prevent chemical reactions during the mixing process, which could affect fertilizer quality or create safety hazards. In addition, feeding should be uniform and steady, avoiding large-scale feeding at once to prevent material accumulation, ensuring an orderly mixing process, and thus guaranteeing the stable operation of the subsequent fertilizer granulators.
Introduction: The “Odor Challenge” in Vegetable Waste Treatment
As a major vegetable producer, China generates over 245 million tons of vegetable waste annually. Improper handling of discarded tomato stalks, cabbage leaves, and similar waste not only occupies space but also produces complex volatile organic compounds (VOCs) during composting, emitting unpleasant odors. A recent study on the co-composting of tomato stalks and cow manure systematically revealed, for the first time, the 58 different VOCs produced during this process and tracked the succession of microbial communities driving the fermentation. This research not only explains the source of compost odors but also provides scientific basis for optimizing composting processes and reducing environmental pollution.
I. The “Odor Map” in Composting: A Symphony of 58 Chemical Compounds
During the 40-day composting cycle, researchers detected a surprising 58 volatile organic compounds. These substances form a complex chemical symphony, including nine major categories: sulfur-containing compounds, alcohols, esters, aldehydes, ketones, halogenated hydrocarbons, aromatic hydrocarbons, alkanes, and alkenes.
Who are the main “culprits”?
Not all detected compounds produce noticeable odors. The study showed that seven substances exceeded the human olfactory threshold: methyl sulfide, ethanol, n-butanol, ethyl acetate, acetaldehyde, butyraldehyde, and α-pinene. Additionally, ammonia (NH₃) was a significant odor contributor.
Methyl Sulfide—This substance, smelling like rotten cabbage, is one of the most important sulfurous odor components in compost. The study found its concentration peaked around day 20 (0.1926 mg/m³). Interestingly, its production is closely related to the presence of anoxic zones within the compost pile. When turning frequency decreases, anaerobic microenvironments easily form inside the pile, promoting methyl sulfide generation.
Ammonia—Persists throughout the composting process as a byproduct of nitrogen transformation. Its production is directly related to the efficiency of nitrogen loss in composting.
Unexpected Discoveries
The study also detected a large number of aromatic hydrocarbons (18 types), likely related to the added cow manure. Aromatic compound precursors in cow manure are converted into these volatile substances by microbial action. Although various alkanes (17 types) were detected, their concentrations were low, contributing little to the overall odor.
II. The Dance of Temperature and the Breath of Oxygen
The composting process involves dynamic changes in temperature and oxygen. The study found:
Temperature Changes: By the 4th day of composting, the temperature exceeded 50°C. The high-temperature period (>55°C) lasted over 15 days, sufficient to kill pathogens and ensure compost sanitization. The temperature curve showed a typical rise-then-fall pattern, reflecting the intensity of microbial activity.
Oxygen Consumption: Oxygen concentration showed fluctuating changes. During days 20-25, when compost temperature remained high and microbial activity was vigorous, oxygen consumption peaked, and oxygen content within the pile reached its lowest. Increasing the turning frequency at this point (from once every 3 days to once every 2 days) effectively increased oxygen concentration and alleviated local anaerobic conditions.
III. The Invisible Workers: Microbial Community Succession
Composting is essentially a microbe-driven biotransformation process. High-throughput sequencing revealed the fascinating succession of bacterial and fungal communities:
The Bacterial Kingdom: Four Phyla Dominate
Firmicutes, Chloroflexi, Proteobacteria, and Actinobacteria were the dominant bacteria during composting, constituting over 80% of the total bacterial community.
In the initial composting stage (1-15 days), the abundance of Firmicutes increased; this phylum includes many species capable of decomposing cellulose and hemicellulose. The abundance of Chloroflexi gradually increased in the early stage, peaking around day 25 before declining. At the genus level, the abundance of Bacillus increased continuously from start to finish, directly related to its cellulose-degrading ability.
The Fungal World: Three Major Groups Take Turns
Ascomycota, Basidiomycota, and Mucoromycota were the dominant fungal groups.
Ascomycota dominated throughout the composting process; these fungi are widespread and can degrade lignocellulose. During days 1-10 of composting, as temperature rose, thermophilic fungi like Thermomyces rapidly multiplied and became dominant. From days 10-20, Thermomyces was replaced by Mycothermus, which may play a key role in decomposing remaining macromolecular substances.
Microbial Association with Odor
The study also identified microorganisms significantly associated with ammonia production. Among bacteria, genera like Desulfitibacter, Paenibacillus, and Haloplasma were related to ammonia concentration; among fungi, genera like Meyerozyma, Alternaria, Hapsidospora, and Aspergillus were closely associated with ammonia production. These findings provide potential targets for controlling compost odor by regulating microbial communities.
IV. Principal Coordinates Analysis: Visualizing Community Changes
Using Principal Coordinates Analysis (PCoA), researchers visually demonstrated microbial community changes:
Bacterial communities were relatively stable in the first 25 days, with sample points clustered closely; after 25 days, community structure changed noticeably with oxygen concentration variations.
Fungal communities underwent three distinct succession stages: the low-temperature period of the first 5 days, the high-temperature period after heating, and the mature stabilization period after 20 days. The fungal community structure differed significantly in each stage.
V. Practical Implications: How to Reduce Compost Odor?
Based on this research, we can derive practical suggestions for reducing odor in vegetable composting:
Optimize Turning Strategy:During the high-temperature, high-oxygen-consumption period around days 20-25, appropriately increase turning frequency to reduce the formation of anaerobic microenvironments, thereby lowering the production of malodorous substances like methyl sulfide.
Adjust Feedstock Ratio:Pay attention to the proportion of cow manure added to avoid excessive aromatic compound precursors entering the composting system.
Inoculate Functional Microorganisms:Consider inoculating microbial agents that efficiently degrade sulfur-containing compounds or fix ammonium nitrogen.
Process Monitoring:Use methyl sulfide and ammonia concentrations as indicators for composting process monitoring, adjusting process parameters promptly.
From Odor Management to Efficient Fertilizer Production
The scientific insights into odor formation during organic fertilizer fermentation directly inform the optimization of industrial-scale organic fertilizer manufacturing. Understanding microbial succession and volatile compound production allows for the refinement of fermentation composting technology for organic fertilizer. Key to this is implementing precise fermentation composting turning technology to manage aeration and temperature, thereby minimizing malodorous emissions and enhancing the efficiency of the decomposition process within a complete organic fertilizer production line.
Following this optimized, scientifically managed fermentation, the stabilized compost proceeds to the final processing stage. Here, an organic fertilizer granulator—such as an innovative new type two in one organic fertilizer granulator that combines mixing and shaping—transforms the material into uniform pellets. This granulation step is a core component of both standard and bio organic fertilizer production line configurations. The entire workflow demonstrates how fundamental research on composting biochemistry is applied to engineer efficient, environmentally sound systems that convert challenging organic waste into valuable, market-ready soil amendments.
Conclusion
Co-composting of vegetable waste and cow manure is a complex biochemical process accompanied by the production of diverse volatile organic compounds and dynamic microbial community succession. Understanding the chemical nature of these odors and their relationship with microbial activity is key to developing efficient, low-odor composting technologies. This study not only provides theoretical guidance for the resource recovery of vegetable waste but also contributes important scientific basis for the green transformation of the composting industry and sustainable agricultural development. In the future, based on these findings, we can design smarter composting systems that minimize environmental impact while transforming organic waste, truly realizing the circular agriculture dream of “turning waste into treasure.”
