An important index of composting is pH, because microorganisms can survive only under appropriate pH conditions; thus, the composting system should be maintained at a certain pH range.
Furthermore, the pH reflects the concentration of organic acids and other acids or alkalis that harm the growth of crops. shows the change in the pH value. The pH value in DHAF was 6.2
at the beginning of the process and continued to increase reaching the highest level of 8.2 at the end of the process; this was owing to sufficient supplementation of oxygen in DHAF, acid-type compounds could be rapid been degraded without accumulation.