water mark moisture blocks to
t
growing season to control growth
t
ensiometers and more expensive probe a
for a range of soils is the
echnologies. My most reliable method w
nd save water. It normally coincides
e
growth. Each type of fruit has a
ith the period of slowest fruit
more can be learned about it at
vapotranspiration method and much d
www.farmwest.com.
given that each variety can have a
ifferent timing, and each variety,
different maturity date will require a
Okanagan-Similkameen, but most
One of the least-used here in the different program to take advantage
effective in terms of soil improvement
of the most water savings without
and efficient use of water, is mulches in
compromising fruit quality.
the plant row. A considerable amount of
research has been conducted at the
reduced with the removal of excess
The impacts of drought are
Pacific Agri-food Research Centre by
shoot growth, fruit removal to save
Dr. Eugene Hogue and his colleagues,
the trees, and finally a dehorning of
and others around the world.
trees where main branches are
removed down to the basic structure,
the major aspects of good soil and water
The use of mulches has been one of to save the trunk and root systems.
management for a very long time. Now
This is of course extreme, but a long
research is providing some of the
term drought, requires actual
detailed reasons as to why mulching is a
survival of the trees. In this last case,
good idea and how it works.
once better moisture conditions have
JUDIE STEEVES
returned growth will start and full
usually very coarse materials, used at a
Wood chips and bark, which are fruiting structure will come back. In
minimum of nine or 10 cm (three to
Low lake levels are a symptom of the
this almost worst case scenario the
four inches) acts as a weed barrier, if
drought conditions being experienced
orchard will be back in production in
more than 10 cm of mulch is added
in the Okanagan-Similkameen.
two to four years.
there will be no greater weed control.
period of years to be of real benefit.
All these stages, from normal
to maintain water vapour levels at the
The mulch acts as transition medium
Mulching in particular requires several use efficiency, to long range planning
production efforts to improve water
soil surface that results in retention of
years to achieve full soil enhancement with mulches, will require good
soil moisture. Also, when rain or water
benefits that influence water extension efforts by packinghouse staff,
from irrigation lands on the mulch, it
management. But mulching will have and water purveyors.
intercepts and slows the movement of
significant impact as a surface
the water. There will be virtually no
application immediately. research effort is required to more
I would also suggest that more
runoff, as opposed to bare soils with no
thoroughly examine the extreme
mulch.
efforts involve much tougher measures.
More extreme drought management
A switch over to drip irrigation is one, if
approaches to tree survival and
maximizing fruit volumes and quality
with the soil result in physical changes
Finer mulches and mulches mixed
drip is not already in place. under Okanagan conditions.
to the soil by providing additional
carbon. It is brought to lower soil levels
be used at specific times during the
Regulated deficit irrigation (RDI) can
Peter Waterman can be contacted at
— Retired grower and horticulturist
by earthworms and other organisms, as
a result the soil becomes more porous
and open and there is a greater
infiltration rate of water.
Proud Supplier of Quality
holding capacity due to these processes.
This is combined with a greater water
Steel & W ire Products
The end result is a greater efficiency in
utilization of water. These
improvements have been noted by a
to Orchards & V ineyards
number of researchers (Stephenson and
Shuster, 1945, Robinson 1988, and
for 30 Y ears
Merwin et al 1994).
concern that this sort of mulch will add
There has been a great deal of
TT hh
too much nitrogen to the soil and affect
other minor elements. This occurs when
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coarse materials are actually mixed with
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depriving the crop of nitrogen and some
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must be planned and done over a
Much of drought mitigation efforts
3174 Mt. Lehman Road
Abbotsford, BC (604) 856-3391
18
British Columbia FRUIT GROWER • Winter 2009-10
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