Handbook for Irrigation of Wine Grapes in South Africa

Chapter 4

In situations where irrigation water is limited, full surface flood irrigation can be converted to furrows (Fig. 4.27). Irrigation water can be applied more efficiently by using furrows (Fig. 4.28) instead of full surface irrigation (Table 4.2). Another possible option is to make borders on each grapevine row, and then apply the irrigation in alternate work rows (Fig. 4.27C). After two to three weeks, the irrigation is applied in the “dry” work rows. This means that a set of alternative work rows will be irrigated every four to six weeks. Irrigation in alternate rows has some similarity to the PRD approach where the objective is to reduce vegetative growth and improve water use efficiency in drip irrigated vineyards without compromising yield. In fact, it was shown that it is possible to reduce vegetative growth, improve WUE and maintain comparable yields with furrows or by means of irrigation in alternate work rows (Table 4.2). Since furrows wet a smaller fraction of the available soil volume, it may lead to water deficits that could cause reduced vegetative growth and yield losses. However, this can be prevented by applying the irrigations more frequently (Table 4.3). Where flood irrigation was applied either at 14 day or 21 day intervals on the grapevine row in 1.5 m wide furrows (Fig.4.28A), it had no effect on grapevine

A

B

C

FIGURE 4.27. Schematic illustration of the difference between (A) full surface border, (B) furrows and (C) irrigation in alternate rows.

IRRIGATION OF WINE GRAPES 89