At the beginning of the experiment, samples were
taken from the fertilized soils (both non-autoclaved and
autoclaved), and their DTPA-extractable Zn, iron (Fe),
copper (Cu) and manganese (Mn) concentrations were
determined. The extractable Zn concentrations of the
treated soils ranged from 0.17 to 0.20 mg kg−1 in the
low-Zn group and from 2.32 to 2.44 mg kg−1 in the
high-Zn group. Neither autoclaving nor P applications
had any effect on the extractable Zn concentration.None
of the treatments affected the extractable concentrations
of Fe and Cu, which ranged from 2.83 to 3.04 mg kg−1
and from 0.62 to 0.65 mg kg−1, respectively. However,
autoclaving greatly enhanced the extractable Mn concentration
(from 1.22 to 6.52 mg kg−1 on average), and
higher P applications reduced the extractable Mn by up
to 20 %.