Joint International Conference on Long-term Experiments ...

LE and KCl-EDTA extracted similar amounts of Zn and Cu and CaCl2- DTPA extracted
much smaller amounts both for Zn and Cu (approximately half-third as much) than the
other two extractant. The thirst two extractant were acidic (pH 4.6 and pH 4.35
respectively), thus KCl-EDTA and LE solved such micronutrient forms e. g. Zn and Cu
oxides-hydrates, Zn and Cu carbonates which can not be solved by CaCl2- DTPA at pH
7.2.
As we expected for each extractants the extracted Cu concentrations were the
largest in case of clay, followed by loam and the smallest for sand. Zn concentration
followed the same tendency for each extractant, but here we got greater values of
averages for sand than for loam.
By he investigated methods the different soil solution ratio and pH influence the
accurate measurement of low concentrations. Extracts of KCl-EDTA with 1:2 soil
solution ratio are better measurable than LE extracts with 1:10 soil solution ratio.
DTPA-CaCl2 solution was buffered to pH=7.2, thus the extracted amounts were smaller
than that of KCl-EDTA solution.
Results of the correlation analysis show (Table 4, Table 5) that in spite of the small
number of samples the extractant concentration of the three methods vary
proportionately. Former similar results were experienced by Balla Kovács et al. Though
the extracted amounts of Cu are similar for KCl-EDTA and LE, the correlation between
these two extractants is not greater than the correlation between these and DTPA-CaCl2
according to the summarised data. When we sorted the soil samples by texture in some
cases the correlation data were better than the summarized data, but in case of Zn we
got worse correlation for loam, and in case of Cu the correlation coefficients were
smaller for sand and loam.
Classifying the soils by lime content, for calcareous soils in case of Cu correlation
coefficient between LE and KCl-EDTA was greater than between DTPA-CaCl2 and the
other two extractant. Contrasted with the other two extractants, buffered DTPA-CaCl2
do not solve Cu forms attached to carbonates, which causes the differences in the
correlation coefficients.
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