Handbook for Irrigation of Wine Grapes in South Africa
Figure 5.2 Figure 5.2 The pH in the river and municipal water tended to be slightly higher than in the rainwater (Fig. 5.3). Higher levels of cations in the river and municipal water caused the EC to be higher, compared to the rainwater. The SAR in all the waters was generally less than 1.5, which is far below the norm of 5 units (Fig. 5.3).
10 12 14 16 18
10 12 14 16 18
Na K Ca Mg Na K Ca Mg
0 2 4 6 8
0 2 4 6 8
Element concentration (mg Ɛ) Element concentration (mg Ɛ)
Rain at Citrusdal
Rain at Cape Town Rain at Cape Town
Rain at Kleinmond Rain at Klei mond
Holsloot River Holsloot River
Stellenbosch municipality Stellenbosch municipality
Rain at Citrusdal
FIGURE 5.2. Basic cation concentration in rainwater collected at Citrusdal and Cape Town, rainwater harvested at Kleinmond, as well as water from the Holsloot River near Rawsonville and the Stellenbosch municipality (Mulidzi, 2016 and references therein).
Figure 5.3 Figure 5.3
10 12 14 16 18 20
10 12 14 16 18 20
pH EC SAR pH EC SAR
0 2 4 6 8
0 2 4 6 8
pH, EC & SAR pH, EC & SAR
Rain at Citrusdal
Rain at Cape Town Rain at Cape Town
Rain at Kleinmond Rain at Klei mond
Holsloot River Holsloot River
Stellenbosch municipality Stellenbosch municipality
Rain at Citrusdal
FIGURE 5.3. The pH, EC (mS/m) and SAR in rainwater collected at Citrusdal and Cape Town, rainwater harvested at Kleinmond, as well as water from the Holsloot River near Rawsonville and the Stellenbosch municipality (Mulidzi, 2016 and references therein). The EC was not determined at Kleinmond.
104 CHAPTER 5 – IRRIGATION WATER QUALITY
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