Both in PBR and CBR treatments, the pH value (Fig. 2)
of the LS declined with increasing input rate, while the
YS showed the opposite trend. Interestingly, both of the
changes were tending towards neutral (pH 7). The pH of
LS decreased from 8.0 to 7.4 and 7.6 with 6% PBR and
CBR addition for 1 month, respectively. On the contrary,
the pH of YS increased from 5.3 to 6.4 and 6.8 with 6%
PBR and CBR addition for 1 month, respectively. This
result indicated that biogas residue might act as a buffer
to adjust the acidity or alkalinity of soil. In the time series,