3.3.Average well color development
During cultivation, the increase rate of AWCD slowed down after 5 days (Fig. 2); AWCD peaked on day 8 and was stable afterwards. Among the eight treatments, ANE showed the highest metabolic rate; the AWCD of ANE increased from 0 to around 1.37 after 8 days. Treatment MN0 showed the lowest metabolic rate, and AWCD increased to around 1.13, indicating a less efficient carbon substrate use. This shows that incubation time has an effect on microbial activity in the examined systems. In the stable period, there were significant differences in the AWCD among the microbial communities from alfalfa treatments (P < 0.01), following the order ANE > AE > AN0 > A0, suggesting that with increasing incubation time, the metabolic activity of the alfalfa microbial community also increases. We observed significant differences in AWCD among the microbial communities of the mulberry treatments (P < 0.01), following the order ME > M0 > MNE > MN0. The AWCD in the treatments ME, M0 and MNE was increased by 23.8% (P< 0.01),21.5% (P < 0.01), and 19.04% (P < 0.01), respectively, compared to MN0.