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Soil sampling and analysis
The first number of the assessment has a value from 1 to 3; 1 being non-saline, 2
potentially saline and 3 saline. The second number has a value from 4 to 6; 4 being
non-sodic, 5 potentially sodic and 6 sodic. A sodic soil is defined as a soil with a low
soluble salt content and a high exchangeable sodium percentage (ESP), with a usual
ESP > 15 (SOIL CLASSIFICATION WORKING GROUP, 1991). A code 1,4 soil is
described as suitable for irrigation, a code 2,5 soil as poorly drained and not suitable
for irrigation and a code 3,6 soil as not suitable for irrigation.
A pH test and a water content test were done on both samples. The pH of three
different replicate samples was measured. Soil was mixed 1:1 (v/v) with water and
homogenized with a stirrer apparatus. After about an hour the soil samples were
vacuum filtered through Whatman No.1 filter papers and their pH was measured. The
water content was calculated by weighing the soil, placing the soil in a drying oven
set at 110°C and then subtracting the mass after no weight loss could be observed
from the initial weight.
3.3 RESULTS
The colour of the two samples suggests that the drainage conditions of sample 1 is
superior to that of sample 2 (DONAHUE et al., 1983) (Figure 3.1). Sample 1 also had
more leaf and root material than sample 2, suggesting that it has more organic
matter, and therefore a higher nutrient content, than sample 2 (DONAHUE et al.,
1983). It is notable that sample 2 appears more aggregated and dense.
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