In organic fertilizer production, fermentation of a single raw material often fails to achieve ideal results—livestock manure has a high nitrogen content but insufficient carbon source, easily producing ammonia volatilization; agricultural waste such as straw and rice husks has a high carbon content but lacks nitrogen, resulting in a long fermentation cycle. Mixing the two for fermentation to achieve a balanced carbon-nitrogen ratio has become the standard process for large-scale organic fertilizer production. However, the complexity of the characteristics of the mixed raw materials places higher demands on the turning and composting equipment. This article analyzes the equipment adaptation and process optimization techniques for the mixed fermentation of livestock manure and agricultural waste.
Chemical-Nitrogen Ratio Balance and Uniform Oxygen Supply The core of mixing livestock manure (e.g., chicken manure C/N 5-10, pig manure C/N 10-15) with agricultural waste (straw C/N 60-80, rice husk C/N 70-100) lies in adjusting the overall carbon-nitrogen ratio to the ideal range of 25-30:1. Studies have shown that a mixture ratio of 45% agricultural waste, 25% livestock manure, and 30% auxiliary materials yields the best fermentation results. The mixed materials need to be turned over to ensure uniform oxygenation. Uneven turning will cause denser manure particles to sink, forming anaerobic zones, while lighter straw will float on the surface and fail to decompose, leading to a prolonged fermentation cycle and nutrient loss.
Adjusting Turning Equipment Parameters for Different Mixing Ratios
The turning parameters for the mixed materials need to be dynamically adjusted based on the proportion of livestock and poultry manure. When the manure proportion is high (>50%), the material has high moisture content and high viscosity, making it prone to clumping and compaction. In this case, the turning frequency needs to be increased—studies show that turning every two days yields the best degradation effect, with optimal pH, moisture content, and C/N ratio. The turning depth should be controlled at 1.2-1.5 meters to prevent bottom compaction. A low to medium speed (100-150 r/min) is recommended to avoid material splashing.
When the proportion of fibrous materials such as straw is high (>60%), the material is loose but has high resistance. The turning frequency can be increased to once every 3-4 days, but the turning depth needs to be increased (1.5-1.8 meters) to ensure thorough mixing of the bottom material. The rotation speed needs to be increased to 180-220 r/min, using the impact force of the blades to cut long fibers and promote material refinement.
Successful mixed fermentation begins with raw material pretreatment. A chain crusher can crush straw and rice husks to 2-5 cm; excessively long fibers are prone to tangling in the equipment. A semi-wet material crusher can process fresh manure with a moisture content of 25%-30%, refining the material to below 5 mm. The crushed raw materials are then uniformly mixed in a horizontal mixer according to the specified ratio to avoid stratification during fermentation, where “manure piles up like manure, and straw piles up like straw.” The mixing time is recommended to be 5-8 minutes, until the material is uniform in color and free of lumps.
The turning process must be matched to the fermentation stage of the mixed raw materials. During the high-temperature period (55-65℃), turning should be done every 2 days to ensure sufficient oxygen and uniform temperature; during the cooling period, turning should be done every 5-7 days to reduce heat loss. A study in Egypt showed that using a kinematic parameter of 35 (corresponding to higher turning intensity) and turning every 7 days can shorten the composting cycle of rice straw and livestock manure to 10 weeks.
During turning, attention must be paid to changes in material moisture. For piles with a high proportion of manure, moisture evaporates quickly in the later stages of fermentation; this can be addressed by spraying water during turning to bring the moisture content to 55%-60%. For piles with a high proportion of straw, the surface layer needs to be compacted during turning to reduce moisture loss.
For the specific needs of mixed fermentation of livestock manure and agricultural waste, our company offers a series of equipment selection solutions. Large wheeled compost turners feature a spiral blade design, which can lightly cut the straw while turning, making them particularly suitable for mixed raw materials with a fiber content of 30%-50%. Trench-type compost turners come standard with a leachate collection system and variable frequency speed control, precisely adapting to mixed fermentation scenarios with a high proportion of high-moisture manure. Equipped with a semi-wet material crusher and a twin-shaft mixer, seamless integration from raw material processing to turning and fermentation is achieved.
Mixed Fermentation of Livestock Manure and Straw
The success of mixed fermentation hinges on the precise application of fermentation composting turning technology. This process begins with accurate raw material formulation. A multiple silos single weigh static batching system can precisely meter the ratios of livestock manure and agricultural waste, ensuring the optimal C/N ratio for rapid decomposition. The blended mixture is then processed by an agriculture waste compost fermentation machine. The choice of machine depends on the specific mix. For a blend with a high proportion of fibrous straw, a large wheel compost turner or a windrow composting machine is often preferred, as their powerful rotors and large wheels can effectively cut and mix long fibers. For mixes with a higher proportion of sticky manure, a trough-type compost turner offers controlled aeration and leachate management. A chain compost turner provides a versatile option for smaller, diverse operations. Regardless of the equipment, the core principle remains: to homogenize the carbon-rich and nitrogen-rich materials, supply oxygen to the active zones, and regulate temperature and moisture. Mastering the parameter adjustments—turning frequency, depth, and speed—for different mixing ratios is what transforms this blend of “manure and straw” into a stable, nutrient-balanced, and high-quality organic fertilizer.
