Abstract:
Ash resulting from biomass energy resource utilization contains a wide range of metal oxides and hydroxides, which may
influence the capacity of the ash to be used as a soil amelioration material. This study aimed to assess the effects of different
ashes on changes in soil carbon (C) mineralization and soil microbial biomass carbon (MBC) in reclaimed mining soils (RMSs).
Different levels (0, 25, 50, and 75 Mg ha−1) of three ashes (rice husk, oil palm shell, and coal fly ash) were applied to 10-year
RMS for a 120-day incubation period. Carbonmineralization was measured over the 120-day incubation period, while MBC and
selected chemical properties were quantified at the end of the incubation period. The results of the study showed that the
application of rice husk and oil palmshell ash at all levels and coal fly ash at low levels (≤ 25 Mg ha−1) increased Cmineralization
and MBC. However, the C mineralization and MBC of the soil decreased significantly when the amount of added coal fly ash
reached 75Mg ha−1. These decreases in C mineralization andMBC may be ascribed to the harmful effect of high amounts of coal
fly ash on microbial activity and the increased specific surface areas and contents of Ca, Mg, oxalate- and dithionite-extractable
iron and aluminumin soil with high amounts of added coal fly ash. This study demonstrates that the application of different types
of ash to RMS leads to different C mineralization and soil MBC responses.
Keywords Organic carbon stabilization . Decomposition . Iron oxide . Aluminum oxide
