Handbook for Irrigation of Wine Grapes in South Africa

FIGURE 4.12. Examples of micro-sprinklers with self-cleaning, wobbling heads.

The radii of micro-sprinkler wetting patterns may vary from approximately 2 to 4 m. The radius will depend on the design of the micro-sprinkler nozzle and the discharge rate. The latter depends on the orifice of the micro-sprinkler base. In most cases, micro-sprinkler systems are designed to wet the total area in vineyards. However, some static micro-sprinklers are designed to distribute the water in strips on the grapevine rows or in fractions of a circle. Wetting patterns of micro- sprinklers may vary from 360° to as narrow as 40° (Fig 4.13). In practice, static micro-sprinklers with strip or fractional wetting patterns are rarely used in vineyards. However, strip wetting can be useful to reduce the risk of runoff losses if the soil is ridged. It must be noted that strip or fractional wetting can only be obtained with static micro-sprinklers. The pros and cons of attachments used to restrict the water distribution patterns around micro-sprinklers are discussed in Chapter 7.

360ƒ (15 streaPs)

360ƒ (12 streaPs)

300ƒ (10 streaPs)

180ƒ (8 streaPs)

280ƒ (open)

270ƒ (open)

90ƒ (open)

180ƒ (open)

40ƒ strip

FIGURE 4.13. Examples of micro-sprinkler wetting patterns.

80 CHAPTER 4 – IRRIGATION SYSTEMS