Agriculture Reference
In-Depth Information
Box 4.7
(continued)
implemented, the coefficients or factors are scaled down during this phase because,
when some water stress occurs, the actual
ET
is less than the adjusted
ET
.
Table B4.7.1
Crop Factors and Crop Coefficients for Vines at Different Growth Stages
in a Temperate Climate
Crop factor
C
f
a
Crop coefficient
C
c
b
At the growth
stage of:
Nostress
RDI
c
Nostress
RDI
c
Bud burst
d
0.2-0.3
0.2-0.3
0.2-0.3
0.2-0.3
Flowering
0.35
0.35
0.45
0.45
Fruit set
0.45
0.25
0.6
0.35
Veraison
0.5
0.3
0.6
0.45
Harvest
0.5
0.5
0.6
0.6
Postharvest
0.25
0.25
0.3
0.3
a
The crop factors are for healthy vines growing on a sandy loam soil on a single trellis up to 2 m
high,withamown,mid-rowcovercrop.hecanopycoverageincreasesfrom10%ofthegroundat
budburstto40%atveraison.
b
The crop coefficients are for similarly managed vines and canopy cover, except that the mid-rows
are bare. Crop coefficients for vines with a cover crop would be slightly larger.
c
Regulateddeicitirrigation(RDI)appliedfromfruitsettoveraisontomaintainsoilwatersupply
betweenthenostressandstresslimit(see“SoilWaterRetentionandPlantAvailableWater,”this
chapter).
d
hevalueatbudburstdependsonwhetherthesoilsurfaceismoistenedbyspringrains(higher
value)ornot(lowervalue).
CompiledfromLópez-Urreaetal.(2012),Nicholas(2004),PrichardandVerdegaal(2001),and
Goodwin(1995).
Crop factors and crop coefficients may need to be adjusted for local
conditions, depending on site potential, vine spacing, presence of a cover crop, and
mulching. For relatively small blocks in hot, dry regions, the crop coefficient
C
c
for
afullyirrigatedvineyardatlargecanopycover(>75%)maybe1to1.1,because
of the extra energy transferred to the canopy by hot winds blowing from the dry
surroundings(calledthe“oasisefect”).
increasingly valuable commodity but also reduces the pumping costs of pressur-
izedirrigationsystems.
ControllingtheSoilWaterDeicitthroughIrrigation
Regulateddeicitirrigation(RDI)oferswinegrowersawaytoimprovewateruse
eiciencyandmeettheirobjectivesforcropyieldandfruitquality.Withinthese
broadobjectives,theremaybespeciicobjectivesdependingonthevariety(and
