[en] Landscape Ecological Survey of the Bipindi-Akom II ... - ITTO

IIIB Comparison of soil data analyses in duplo (IRA, Ekona, Cameroon and
ISRIC, Wageningen, The Netherlands)
The comparison of soil data analyses at IRA, Ekona and ISRIC, Wageningen, The Netherlands is
based based on Hommel Hommel & van Kekem's Kekem's mission mission report report (1996). (1996).
Conditions
All soil samples were analyses at IRA Ekona. Some samples were analyses in duplo. Also a
selected set of soil samples were analysed at ISRIC, Wageningen, The Netherlands.
Interpretation
Interpretation
First of all the course with depth of all elements analyses were interpreted. The original data were
compared with the duplo analysis of Ekona and ISRIC.
Results
Texture analysis do not show large variation comparing the data sets of Ekona and ISRIC. The
texture with depth is becoming more clayey. The Ekona gravel data are higher as consequence consequence of
their method of sieving.
The pH H H20 20 and pH KCI are in general a little higher in the Ekona case. However the differences
between the two data sets are always smaller than 0.5 unit.
Organic matter concentration is sometimes a little higher in the surface horizons of the Ekona data
set. The different nitrogen concentrations (Ekona and ISRIC) are comparable. C/N values are
therefore higher, in the surface horizons of the Ekona data. The nitrogen and organic carbon
concentrations decrease with depth.
Available Available and total total phosphorous phosphorous can not not be be compared compared as as consequence consequence of of different different methods methods used.
Both data sets decrease also with depth.
The The exchangeable bases sodium sodium (Na) (Na) and and potassium potassium (K) (K) are are exchangeable exchangeable within within the the data data sets. The The
data do not differ more than 0.2 unit.
Magnesium and calcium have sometimes large differences (> 0.2 unit). The methods used in Ekona
are susceptible to errors if the concentrations of magnesium and calcium in the soil samples are
low. Two third of the Ekona data is more than 0.2 unit (mainly) too high. Nevertheless the
differences in total exchangeable bases between the data sets are mostly smaller than 1 unit (in
meq/lOO g).
Aluminium (AP+) and hydrogen (H+) data differ not more than 1.5 and 0.4 unit, respectively. The
hydrogen data have proportional large differences (> 20%). Nevertheless the differences in
effective cation exchangeable capacity between the data sets are in majority smaller than 2 units.
In general the Ekona data are higher than the ISRIC data.
The Cation Exchange Capacity (CEC) is largely of the same order for the data sets « 2 units).
Differences occur mainly in the surface horizons. The surface horizon CEC values of Ekona are
mainly lower than those oflSRIC.
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