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AWARD WINNING ORGANICALLY PRODUCED WINES |
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| Irrigation |
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Our Vine Yard tour continues
with a look at irrigation practices.
We occupy what is, in essence, the northern
tip of the great Sonoran desert system,
a rain shadow in the lee of western coastal
mountain ranges extending the length of
North America. Our mean annual precipitation
is 300 mm (as compared to Vancouver's
1200 mm). Irrigation is essential for
any large-scale agricultural endeavour
in the Okanagan, and the history of European
settlement in the valley reads like a
tracer line following the old, wooden
irrigation flumes coming down from the
hills to the valley below. (For example,
Coldham Road, which bisects our property,
is named for one of 3 pioneering Peachland
farm families who built the area's first
irrigation system.) Water is a valuable
and political commodity, and many British
Columbia growers have followed with interest
and no small degree of irony the various
Canada/U.S. treaties that always seem
to result in our precious water being
poured, at heavily subsidized rates, onto
American crops which are then dumped back
into our marketplace. Irony aside, we
still think it makes more sense to use
water for crops which feed people (directly
or indirectly) than for nonfunctional,
greedy lawns.
Our irrigation water comes from two sources;
mountain reservoirs at Silver and Lacomo
Lakes feeding into Trepanier Creek, and
Okanagan Lake. The creek system is used
until midsummer, when levels are depleted;
we must then switch to water pumped from
the lake. As organic growers, we are always
conscious of the quality of the water
all around us, as it will have a direct
bearing on the integrity of our organic
system. Anything which affects the quality
of lake or creek water will affect the
quality of our irrigation water; it's
inescapable, and political, once again,
as population density and recreational
use of the lake increases.
Our organic growing guidelines, established
by SOOPA and adopted by COABC, stipulate
that water quality must be tested every
5 years in order to monitor compliance
with minimum guidelines.
It takes a lot of water to irrigate a
Vine Yard, but it takes a lot more to keep
a golf course green. Farmers continue
to be among the valley's most responsible
water users, because they have always
had to pay for irrigation water directly.
Most households in the valley still pay
for their water through taxes rather than
through metering--it is no surprise that
Canadians rank among the world's most
prolific consumers/wasters of water.
We use a combination of two different
watering systems. In the lower Vine Yard,
planted with Riesling and Traminer, we
use drip irrigation (a long pipe with
inserted micro jets, running along the
trellis line), and in the upper Vine Yards,
we use overhead sprinklers. Drip irrigation
is more efficient, as less water is lost
to evaporation and more water is applied
to the area directly around each plant.
However, a drip system is about 5 times
more expensive than an overhead system
to install and maintain.
Irrigation commences in late May, as
the vines begin their first spurt of new
growth. We have experimented with various
irrigation regimens, and have concluded
that deep, long soakings benefit the plants
more than shallow frequent applications.
(We should point out, however, that irrigation
practice continues to be a hot topic for
research; new findings are being published
every year. Grape specialists from the
Agri-Food Canada Summerland Research Station
just down the road from us have been leaders
in this research.) The system, controlled
by an automatic timer, is left on for
10 hours per block, and each block will
be irrigated every 10 to 20 days, depending
on the weather and the time of year.
The Vine Yard's moisture requirements
vary throughout the growing season, with
demand being heaviest in June and July
and lowest in September as harvest approaches
(although new research seems to cast some
doubt on this). There is also some variance
by variety. Monitoring is done through
a combination of past experience, weather
patterns, and techniques as prosaic as
feeling the leaves; if they're hot, or
if they feel limp, it's time to water.
We do not use automatic sensors, although
we are aware of other growers who have
installed them.
What would happen if we decided to stop
irrigating completely? Grapevines benefit
from some water stress during the growing
season, as it forces the plant into ripening
its fruit instead of putting its energy
into producing more foliage. However,
with our light, sandy soil, our lack of
appreciable precipitation or humidity
for most of the summer and the high evaporation
rate, the vines would quickly lapse into
severe water stress without some irrigation,
and would reach their permanent wilting
point beyond which they cannot be revived.
Leaves would begin to die and drop, and
the plant's reduced photosynthetic ability
would decrease its ability to produce
ripe fruit. Berry size would decrease,
as would juice volume. The quality of
the juice would be unbalanced and unsuitable
for good wine. Any bunches which were
approaching ripeness may, with the lack
of leaves, burn in the sun and be damaged,
and would certainly be exposed to increased
predation by birds. Vines with shallow
root systems in poor soil, or vines which
are otherwise compromised by disease or
pests, may perish altogether.
What happens if we irrigate too much?
Vine Yards which are fed lots of water,
particularly those planted in heavier
soils which retain water, appear to be
very impressive, with bushy vigour, deep
green leaf colour and huge clusters of
berries. Unfortunately, while the fruit
volume may be large, the quality is poor.
The grapes take a lot longer to ripen,
and in our growing season, they may not
ripen at all before the plants shed their
leaves. The juice will be high in acid,
low in sugar and lacking in varietal intensity,
and a winemaker will have to work technological
miracles to make something palatable out
of it. In a quality-driven international
wine market, any grape grower who maximizes
tonnage by over watering and over fertilizing
the vines, thereby sacrificing fruit quality,
is not going to be in business for long.
It's all a matter of balance and control.
Too little or too much water are equally
damaging to the plants, to the fruit and
ultimately, to the wine. Our very sandy
soil drains quickly, and in our climate,
we run more risk of too little water than
too much. In addition to careful monitoring
of the irrigation system, we are constantly
working to improve the soil's water retention
by increasing its organic content. (This
is accomplished through cultivation of
ground cover and by the direct addition
of compost.) Keep in mind that our observations
are strictly based on our particular location;
growers in other parts of the valley or
the province, with different soils and
micro climates, have their own stories
to tell. |
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