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