Organic Fertilizer Fermentation Process

Fermentation Process

1.Pretreatment of raw materials: including sorting, crushing, water content and carbon-nitrogen ratio adjustment.

2.Raw Material Fermentation: The cycle usually takes 15-20 days.

(1)The first stage: refers to the two stages of microbial metabolism in aerobic fermentation at medium temperature and high temperature. It refers to the whole process from the initial stage of fermentation, through medium temperature and high temperature, and then the temperature starts to drop. It usually takes 10-12 days.

(2)The second stage: after the first stage of fermentation of the material, there is still a part of easily decomposable and a large amount of difficult to decompose organic matter, which needs to continue to be fermented to make it mature. At this time, the temperature continues to drop. When the temperature stabilizes at about 35-40℃, it will reach maturity, which usually takes 5-10 days.

(3)Post-treatment stage: Post-treatment includes removal of impurities and necessary crushing treatment.

Technological Process

(1)Composting Technology

The ground is compacted before the pile, and then the fermented raw materials such as manure, peat, are mixed and piled in proportion.

(2)Stirring, Turning and Stacking Fermentation Process

The materials are stacked in stacks, which can be arranged into multiple parallel stacks. The cross-sectional shape of the stacks is usually triangular or trapezoidal, with a height of 1-1.5m and a width of 2-3m. The moisture content of the stock after mixing is 55-65%.

In the pretreatment, it is sometimes necessary to crush the raw materials and adjust the particle size of the raw materials. The suitable particle size range is 12-60mm. Crushing and screening can increase the surface area of raw materials, facilitate the reproduction of microorganisms, and increase the fermentation speed. It can be turned over every 4-7 days after stacking, and it can be stopped after 1 month to let it ripen naturally.

Maturity of Fermentation

(1)Appearance change: The intuitive qualitative judgment standard is that the fermentation will no longer undergo intense decomposition, and the temperature of the finished product is lower; the appearance is dark brown or black; the structure is loose; there is no foul smell.

(2)Temperature change: Usually the temperature of the fertilizer pile will gradually drop after the high temperature stage. When the fermentation reaches maturity, the pile temperature will be lower than 40°C.

Chemical Indicators

(1)Changes in the content of organic matter and volatile solids: As the fermentation progresses, the content of fermented organic matter and volatile solids continues to decrease, and finally reaches a basic stability. When it reaches maturity, it can drop by 15-30%. However, this change trend is greatly affected by the source of raw materials. It is not sufficient to use it to measure whether the fermentation is mature.

(2)Changes in nitrogen, C/N ratio and inorganic nitrogen form: During the fermentation process, part of the organic carbon will be oxidized to CO2 volatilization loss, and the quality of the fertilizer pile will be reduced. Since the loss of nitrogen (mainly in the ammoniation stage of organic nitrogen, a small amount of ammonia nitrogen will volatilize) is much lower than the loss of organic carbon, after fermentation, the total nitrogen content in the fermentation tends to rise, and C/N The ratio continues to decrease until it stabilizes. Some studies have pointed out that when the C/N ratio of the piled material drops from 25 to 35:1 to below 20:1, the manure pile will stabilize.