Generally speaking, composting is divided into aerobic composting and anaerobic composting. Aerobic composting refers to the decomposition process of organic materials in the presence of oxygen, and its metabolites are mainly carbon dioxide, water, and heat; while anaerobic composting refers to the decomposition of organic materials in the absence of oxygen, and the final metabolites of anaerobic decomposition are Methane, carbon dioxide and many low molecular weight intermediates such as organic acids, etc. Traditional composting is mainly based on anaerobic composting, while modern composting mostly adopts aerobic composting, because aerobic composting is convenient for mass production and has less impact on the surrounding environment.
Aeration and oxygen supply to the raw material stack is the key to the success of composting. The amount of oxygen demand in compost is related to the content of organic matter in the compost. The more organic matter, the greater the oxygen consumption. Generally, the oxygen demand in the composting process depends on the amount of oxidized carbon.
In the early stage of composting, it is mainly the decomposition activity of aerobic microorganisms, which requires good ventilation conditions. If the ventilation is poor, the aerobic microorganisms will be inhibited, and the compost will be decomposed slowly; on the contrary, if the ventilation is too high, not only the water and nutrients in the heap will be lost too, but also the organic matter will be decomposed strongly, which is not good for the accumulation of humus.
Therefore, in the early stage, the pile body should not be too tight, and a turning machine can be used to turn the pile body to increase the oxygen supply of pile body. The late anaerobic phase is conducive to nutrient preservation and reduces volatilization loss. Therefore, the compost is required to be properly compacted or stop turning.
It is generally believed that it is more appropriate to maintain the oxygen in the stack at 8%-18%. Below 8% will lead to anaerobic fermentation and produce a foul odor; above 18%, the heap will be cooled, resulting in the survival of a large number of pathogenic bacteria.
The number of turnings depends on the oxygen consumption of microorganisms in the strip pile, and the frequency of compost turning is significantly higher in the early stage of composting than in the later stage of composting. Generally, the heap should be turned once every 3 days. When the temperature exceeds 50 degrees, it should be turned over; when the temperature exceeds 70 degrees, it should be turned on once every 2 days, and when the temperature exceeds 75 degrees, it should be turned on once a day for rapid cooling.
The purpose of turning the compost pile is to ferment evenly, improve the degree of composting, supplement oxygen, and reduce moisture and temperature, and it is recommended to turn the farmyard manure compost at least 3 times.
Post time: Jul-20-2022