the acidity or alkalinity soil towards neutral and also
increase the DOC of the soils. Due to the high heavy
metal concentrations in the BR itself, part of the Cu and
Zn leached to the soil solution as exchangeable fraction.
The increase rate of exchangeable Zn was higher than
that of exchangeable Cu. DOC was the limiting factor for
Cu while Zn was controlled by pH. Comparing the two
BRs, PBR presented more agricultural risk than CBR as a
fertilizer. BRs were more adaptable to alkaline soils. An
addition rate of 2% could be a suitable application level of
BRs to the soils per year and perennial application should
prompt concern for and monitoring of heavy metal release