Handbook for Irrigation of Wine Grapes in South Africa

Chapter 4

FIGURE 4.34. An example of a disk filter clogged by sludge and solid material in the irrigation water. Figure 4.35

A

B

FIGURE 4.35. Algae and slime in irrigation water (A) can cause severe filter clogging (B).

Figure 4.36 In order to reduce maintenance inputs and allow almost uninterrupted water flow, filters that flush automatically when they become clogged while irrigation is being applied, are preferred (Fig. 4.36). These filters can either be flushed automatically at regular intervals by means of a time switch, or the flushing can be triggered when the pressure difference up- and downstream of the filter reaches a pre-set value. Irrigation water containing high levels of silt may also cause clogging. In many cases, the risk of sludge deposits in irrigation systems can be reduced by suspending the suction pipe from a float (Fig. 4.37). By doing so, less sludge will be sucked from the bottom of the dam or reservoir.

IRRIGATION OF WINE GRAPES 97