Chicken manure contains abundant organic matter, high levels of N, P, K, and trace elements, making it an excellent raw material for organic fertilizers. Dry chicken manure has an organic matter content of 50%, nitrogen of 3.2%, phosphorus (calculated as P2O5) of 3.1%, and potassium (calculated as K2O) of 2.4%. It is rich in nutrients and contains a large amount of protein, making it a good raw material for making organic fertilizers in current manure.  

1. Main technologies for chicken manure composting treatment

Chicken manure composting fermentation mainly utilizes biological processes combined with advanced mechanical techniques to effectively treat chicken manure. The commonly used process method is aerobic fermentation. Adopting aerobic fermentation, chicken manure compost has fast heating, high fermentation temperature, and short maturation period. Due to its high fermentation temperature, it can effectively kill eggs, bacteria, plant seeds, etc. in chicken manure. Under effective mechanical stirring, its drying effect is also very significant.

The commonly used composting fermentation processes in industry currently include strip stack composting fermentation process and trough aerobic fermentation process.  

Trough aerobic fermentation: This is currently an effective method for treating chicken manure and is also suitable for the commercial production of organic fertilizers from chicken manure, which is conducive to standardized production. It utilizes biological characteristics combined with mechanized technology to fully decompose chicken manure and convert organic matter into organic matter, carbon dioxide, and water using natural or inoculated microorganisms. This method has a short fermentation time and is easy to achieve factory scale production, which is not affected by weather seasons and causes minimal pollution to the environment. It is conducive to the commercial production of chicken manure organic fertilizer. Depending on the equipment, the width of the fermentation tank is generally 6 meters, the depth is generally 1.5 meters, and the length ranges from 50 to 100 meters, which can be designed according to the actual situation.  

Strip style composting fermentation: Strip style composting fermentation is the process of spreading materials into rows and stacking them outdoors or on shelves. Each row of materials is 4-6 meters wide and about 2 meters high, and the length depends on the actual situation. Ventilation pipes can be installed under the material pile, or ventilation facilities can be omitted. The characteristic of treating chicken manure with strip composting is that the material can be placed close to the farmland, without the need for a dedicated factory, but the processing time is relatively long. If the outdoor method is used, it is greatly affected by the weather season.  

To achieve the commercial production and management of chicken manure organic fertilizer, this article mainly introduces the trough aerobic fermentation process. The following data comes from a certain bio organic fertilizer factory. The fermentation tank has a width of 6 meters, a depth of 1.5 meters, a length of 60 meters, a fermentation temperature of 60 ℃, and a fermentation time of 20 days. At 60 ℃, combined with mechanical stirring, the fermentation speed is fast, the fermentation process is easy to control, and is not affected by weather and seasons, which is conducive to large-scale standardized production.  

Fermentation process conditions for chicken manure compost

2.1 Suitable fermentation materials: Organic matter is the main nutrient for composting microorganisms. The requirements of composting microorganisms for carbon (C) and nitrogen (N) elements in organic matter must be maintained at an appropriate ratio, and it is generally believed that the suitable carbon to nitrogen ratio (C/N) is 20-35/1.

The carbon to nitrogen ratio (C/N) of commonly used compost fermentation materials is as follows.

Therefore, according to the ratio of chicken manure to auxiliary materials (usually 3:1), composting auxiliary materials can be selected with a carbon nitrogen ratio of 20-80:1. So common organic materials in rural areas, such as dry straw, corn stalks, fallen leaves, soybean stems, peanut stems, etc., can be used as auxiliary materials for composting fermentation after being crushed.  

2.2 Suitable moisture content for composting: Microbial fermentation humidity is 50-60%, with a maximum humidity of

60-65%, therefore it is best to adjust the moisture content of the material to around 55-60%. When the moisture content reaches 65% or more, there is a higher chance of dead tanks not fermenting.  

According to multiple measurements of chicken manure and auxiliary materials, the moisture content of fresh chicken manure is 80%, the moisture content of auxiliary materials is 10%, and the moisture content of inoculation materials is 40%. In large-scale production, the material from the tank is generally used as inoculum, and the inoculum amount is 10% of the total amount (low requirement). Mix fresh chicken manure, auxiliary materials, and inoculation materials evenly before entering the tank for fermentation. The moisture content of the fermentation material is 60%. Based on the above data, the ratio of chicken manure to auxiliary materials can be calculated to be approximately 3:1.  

2.3 Effective mechanical stirring of chicken manure compost fermentation belongs to aerobic fermentation. In the fermentation tank, due to the high humidity and viscosity of the material at 60-65%, its aeration is extremely poor and requires manual assisted aeration. Mechanical stirring is generally used.  

In actual production, the temperature of the fermentation tank will be affected to some extent by the temperature season. In summer, the temperature in the workshop is above 30 ℃, and the fermentation temperature can reach 60-65 ℃, even exceeding 65 ℃. It can be stirred every hour to facilitate aerobic fermentation of microorganisms and drying of materials. In winter, when the temperature in the workshop is below 10 ℃, the fermentation temperature can only reach 45-55 ℃. Due to the stirring effect, some heat will be taken away, so it can be stirred every 4 hours to maintain high temperature conditions.  

3 Production Technology Management

3.1 Control of Chicken Manure and Auxiliary Materials According to local agricultural conditions, organic materials such as straw, corn stalks, and peanut stems can be used as auxiliary materials. According to the requirements for fermentation moisture, the ratio of chicken manure to auxiliary materials is 3:1. The fermentation tank is 50 meters long, 6 meters wide, and 1.5 meters deep. Therefore, each tank requires 150 tons of chicken manure, 50 tons of auxiliary materials, and 22 tons of inoculation materials. In the fermentation tank, chicken manure, auxiliary materials, and inoculation materials need to be mixed evenly.  

3.2 Control of Inoculation Materials: The decomposed materials from the tank contain a high amount of high-temperature microorganisms, which can be used as inoculation materials and added to the fermentation tank to improve fermentation speed. The general inoculation amount is 10% of the total amount, and 20% can be inoculated in winter.  

3.3 Example of Water Evaporation and Mixing:

Moisture testing and stirring frequency statistics show that when the fermentation tank temperature is around 60 ℃ and stirred twice a day, the total moisture content can decrease by 2%; When the fermentation temperature is around 50 ℃, stirring twice a day can only reduce the total moisture content by 1%. Assuming that each fermentation tank is stirred twice a day, with 150 tons of chicken manure, 50 tons of auxiliary materials, and 22 tons of return materials fed into each tank, the fermentation temperature is 60 ℃, and the fermentation time is 20 days, the following material balance can be calculated:

Therefore, after 20 days of fermentation and stirring for 40 times, the moisture content of the material discharged from the tank can be controlled at 40-45%. After drying or air drying, it can be produced into commercial products. Commercial products require a moisture content of less than 20%. Therefore, one tank can produce 103 tons of finished organic fertilizer (with a moisture content of 20%) per batch.  

After mixing chicken manure, auxiliary materials, and inoculation materials in the tank, the first stirring is recorded as the start time of the fermentation cycle. Generally, after a 3-4 day heating period (7-10 days in winter), it enters the high-temperature fermentation stage. When the temperature of the fermentation tank is higher than 55 ℃, the material can be fully fermented in 15 days, while when it is lower than 50 ℃, it needs to be fermented for 30 days. Therefore, the fermentation cycle in summer is generally 18 days, and the fermentation cycle in winter is 35 days.

If the temperature inside the fermentation tank does not exceed 40 ℃ after entering the tank for 10 days, it can be determined as a dead tank and the fermentation start-up fails. At this point, it is necessary to measure the moisture content in the tank. If the moisture content exceeds 60%, auxiliary materials and inoculation materials need to be added; If the moisture content is below 60%, consider whether the amount of inoculum material added is insufficient.  

4 Conclusion

The trough type oxygen consuming stirring fermentation process is a process of treating chicken manure through effective microbial bacteria, which fully utilizes the microbial and mechanical stirring effects. High fermentation temperature can effectively kill harmful elements such as pathogens, viruses, insect eggs, and weed seeds in livestock and poultry manure. The fermentation and drying time is short, which can achieve factory standardized production. Eliminate odors, convert organic pollutants into nutrients that are easily absorbed by plants, and achieve harmless requirements.