TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Method: (M1) is carried out using the composting apparatus. The fermented organic substance is released from the fermentation shelf through the reticulate bottom to the second stage of the fermentation shelf where high temperature fermentation is carried out, and then to the lower stage, where composting process is further enhanced. EXAMPLE - Organic substance was mixed by shearing or pressurization in a ratio of (in weight%) dry droppings of hen (69), chaff (10) and tap water (21) as described in patent application No.5-105564. A cylindrical container of base diameter 1000 mm, having average pore size of 3 mm was packed with the organic substance to a height of 800 mm. The weight of the packed organic substance was 450 kg. A warm chamber was made using plastic sheets. A test board of the shape of a lattice having 30 mm x 60 mm rectangular opening was installed. The container packed with organic substance was mounted on the test board and fermentation was started. The fermentation temperature was continuously measured using a thermometer inserted into the organic substance. Air circulation in the container in a up-down direction was carried out uniformly. In the initial stage of high temperature fermentation, the moisture content of the organic substance was high. In the later stages, as the temperature increased to 70 degrees C moisture content gradually decreased and as the moisture content decreased the temperature also decreased to 60 degrees C. The moisture content further continued to decrease at 60 degrees C. This showed that as the fermentation temperature increased, the fermentation of organic substance occurred effectively. The oxygen concentration of the organic substance was measured using oxygen measuring device which was 19.8% at 2 hours after the start of fermentation and 18.2% after 20 hours. Thus the air permeability of the organic substance was maintained almost uniformly through the fermentation process.