GEOMORPHOLOGY REPORT - CRC LEME

6.2 EC and pH
6.2.1 Methodology
Soil electrical conductivities were measured to determine the conductivity, salt content and
salt load of the surface materials within 30 cm of the surface. Conductivity also provided a
measure of soil development in landform units of different ages. Measuring pH quantitatively
provides a cross check on field determinations and another way of determining soil evolution
in differently aged landform units.
Measuring salinity and pH in soil was carried out using the 1:5 method. With this method,
10ml of distilled water is placed in a measuring container and small soil particles added until
the volume of the contents of the container increased by 5ml to bring the volume to 15ml.
Additional water is then added to bring the total volume to 30ml. the sample is shaken
intermittently for five minutes and allow it to settle for five minutes. EC and pH probes are
dipped into the solution and readings taken.
6.2.2 Results
The measured EC values ranged between 0.036 and 4.4 dS/m, with the majority (all but
seven) falling below 1.0 dS/m. There is no good trend between conductivity and geomorphic
unit relatively high conductivities (>1.0) are found in units Fs, Fm1, Fm3, and T. However,
the terrace (T) units are on average more saline than those of the floodplain and uplands.
Measured pH values range between 4.45 and 9.45, with the majority of the samples being
acidic. There is a clear trend between increasing age of geomorphic unit and increasing pH.
The youngest geomorphic units are almost entirely acidic, including almost all examples of
unit Fm1. Soils from the terrace unit and uplands are near neutral to alkaline (
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