Agriculture Reference
In-Depth Information
Other Factors in Site Selection
Water for Irrigation
An adequate supply of good-quality water is essential for vineyards that need irri-
gation. In regions of hot, dry summers, such as La Mancha in Spain, the Central
Valley of California, or the Murray-Darling and Riverland regions in Australia,
irrigation water is essential to produce a satisfactory crop. Indeed, during periods
of severe hot, dry weather in Australian inland regions during the “millennium
drought” of 1996-2008, the vineyards that survived best were those where the
irrigation water was applied at the maximum rate just before and during the stress
periods. In cool climate regions, however, irrigation may be only supplemental in
that it is used for vine establishment and when unusually dry conditions occur.
Water for irrigation may come from groundwater, surface water, reclaimed
water, or a combination of these sources. Where a suitable site exists, a winegrower
may construct a farm dam; in other cases, water may be pumped from a river or
lake, or supplied by pipe line as in the Barossa Valley region, South Australia. The
total water requirement for a vineyard will depend on three things:
1. The climate, especially the balance between rainfall and evaporation and
the seasonal distribution of rainfall (see “Evaporation and Transpiration,”
chapter 4).
2. The likely peak demand as determined by the area to be irrigated, grape
variety, planting density, yield objectives, and irrigation method.
3. Additional factors, such as soil storage capacity, whether overhead
sprinklers are to be used for frost control, or a winery is to operate onsite.
Given that irrigation in most modern vineyards is applied through surface
or subsurface drip lines, the likely peak demand will depend on the number of
vines per ha, the number of drippers per vine, and the delivery rate of the drip-
pers. Box 2.3 gives examples of how to calculate the peak delivery rate and total
quantity of water required.
Box 2.3 Water Needs for an Irrigated Vineyard
Drippers for surface drip irrigation have delivery rates of 0.6 to 4 L/hour (hr).
Delivery rates of 0.8 to 1.2 L/hr are preferred for soils in which water entry is slow.
In this case, two or three drippers can be placed in the drip line near each vine for
the required amount of water to be applied during an irrigation (figure B2.3.1).
(continued)
