Handbook for Irrigation of Wine Grapes in South Africa

Chapter 5

yield, compared to untreated water (Myburgh, 2012b). Irrigation water can also be enriched with micro-fine gypsum. Such treatment can only be beneficial if high soil Na in relation to Ca and Mg causes water infiltration problems. If gypsum is added to water that already contains high levels of salt, it can only aggravate the situation by increasing the amount of salts in the soil.

Figure 5.9

A

B

FIGURE 5.9. Example of (A) an inline unit for electro-mechanical, catalytic water treatment and (B) its inlet port showing the grid to create turbulent water flow.

Figure 5.10

5.4.5 EFFECT OF IRRIGATION SYSTEMS Experience has shown that salt-containing fog caused leaf damage in vineyards close to the ocean near Strandfontein along the West Coast (C. Malan, personal communication, 2002). Therefore, saline water should preferably not be applied by overhead sprinklers to prevent direct contact with the leaves. Under-vine irrigation systems, e.g. micro-sprinklers and drippers, can deposit salts on grapevine trunks (Fig. 5.10), but trunks can be shielded to avoid possible salt damage (Fig. 5.11).

FIGURE 5.10. Salt deposits on grapevine trunks where saline water was applied through drippers near Vanrhynsdorp.

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