1. Temperature change: Monitoring the temperature change during the fermentation process is one of the important indicators to judge whether the fermentation is complete. In the early stage of fermentation, due to the vigorous activity of microorganisms, a large amount of heat will be generated, causing the compost temperature to rise rapidly. Generally speaking, the compost temperature will rise to 50℃ - 70℃ or even higher within a few days.

As the fermentation proceeds, the decomposable organic matter gradually decreases, the microbial activity weakens, and the temperature gradually decreases. When the compost temperature is close to the ambient temperature and there is no obvious temperature rise, it can usually be considered that the fermentation is basically completed.

2. Appearance changes:

Volume and color: Organic materials before fermentation are usually large in volume and loose in structure. After fermentation, the volume of the material will be significantly reduced, generally by 30% - 50%. This is because during the fermentation process, organic matter is decomposed, water evaporates, and the activity of microorganisms makes the material more compact.

The color will also change, generally from the original raw material color to dark brown or black. This is due to the color of substances such as humus produced by microorganisms decomposing organic matter.

Texture and structure: The texture of fermented organic fertilizer is relatively loose, and it feels soft when squeezed by hand, without obvious lumps or adhesion. The material that has not been fermented may have agglomeration and a hard texture.

From a structural point of view, the particle size of the fermented organic fertilizer is relatively uniform, with a certain porosity, which is conducive to the circulation of air and water.

3. Odor change: In the early stage of fermentation, organic materials will emit pungent ammonia, hydrogen sulfide and other unpleasant odors. This is because during the fermentation process, proteins, sulfur-containing compounds, etc. are decomposed by microorganisms to produce these odorous substances.

As the fermentation proceeds, the odor gradually weakens. When the fermentation is completed, the organic fertilizer should have a light earthy or humus smell, and no longer have a noticeable pungent smell.

4. Chemical index detection: During the fermentation process, the pH value of the material will also change. Generally speaking, the pH value of the initial material may vary depending on the raw material. During the fermentation process, the pH value will gradually tend to be neutral or slightly alkaline. When the fermentation is completed, the pH value is usually between 6.5 and 8.5.