After bumper yields lifted almond
growers’ hearts and spirits in 2020,
it’s still too early to say how 2021 will
turn out. First indications will come
with February’s bloom, but it’s still not
too late for some nutrition planning to
maintain yield potential should 2021
deliver another season of almond friendly
conditions, says agronomist
Francisco Rivera, of California-based
“Why are almonds known as a
‘superfood’?” Francisco asks. “Because
they’re packed with potassium, calcium
and protein ‘built’ from nitrogen.
“Average nut set reported by USDA in
California was 5,645 kernels, a 20 per cent
increase on 2019,” he points out. “All those
extra kernels demand a lot of nutrients
from the tree. It’s easy to see how, after
such a heavy crop, nutrient levels in the
tree can fall dangerously low.”
Francisco says it’s essential that growers
take steps to raise these nutrient levels
before the tree needs them again.
“Nitrogen for vegetative growth, bud
formation and nut protein; potassium for
growth, water optimization and nut-fill; and
calcium for high quality, disease-free nuts.”
But of the three nutrients in question,
calcium is one to watch. “Very early in the
season, even after a heavy harvest the
previous year, trees will continue to take
nitrogen and potassium from reserves,
at least until top-up treatments can be
applied ahead of key events such as fruit
set and during development.
“Calcium, however, is a different matter —
and it’s the first golden rule to remember:
crops cannot store excess calcium.”
Unlike potassium and many other
nutrients, Francisco explains, plants have
no capacity to store reserves of calcium.
In fact, once they’ve topped-up their
calcium storage — in the calmodulin
proteins between the cell wall and cell
membrane — any excess calcium is
ejected through the leaves, even if fruit or
nuts are displaying calcium deficiencies.
“This also sheds light on why tissue
testing for calcium is so unreliable,”
warns Francisco. “Not only is there
no connection between leaf tissue
calcium and fruit tissue calcium, but the
difference between acceptable levels and
deficiency can be as small as 2ppm —
outside any analytical tolerances.”
The second golden rule is that calcium can
only move up. “Plants can’t move it from
one place to another,” says Francisco,
“because it’s not phloem mobile. Instead
it moves through the xylem, following
water through the tree from the roots to
the places of highest water loss — usually
the top-most leaves.
“This explains why any water-related
conditions — drought, waterlogging,
wind — can bring about calcium-related
Finally, calcium transport into cells is
directly influenced by the plant hormone
auxin. If there’s no auxin present, then
crops won’t absorb calcium properly,
irrespective of how much is applied.
“Auxin is involved in cell division,” explains
Francisco. “New tissue — as found in
developing nuts — has high auxin levels
and can absorb good levels of calcium.
But once the nut has all its cells and shifts
to cell expansion — the maturing nuts —
its ability to absorb calcium decreases
“Young nuts absorb calcium well;
maturing nuts will struggle.”
Understanding this aspect of the tree’s
physiology was crucial in helping a British
agri-tech company, Levity Crop Science,
create the science needed to support
better calcium nutrition. Its research team
came up with two technologies, LimiN and
LoCal, to circumvent the problem. Both
are available in the U.S. through a unique
partnership between OMEX® and Levity.
“This technology is like nothing else in the
market,” enthuses Francisco. “When we
evaluated the Levity tech as an additive
to our own products, we couldn’t wait to
incorporate them and bring their benefits
to our customers here.
“We incorporated the LimiN technology
within Cell Power® SizeN®, co-formulated
with calcium,” he continues. “LimiN
comprises a stabilized amine nitrogen,
which emphasizes root growth and a
good compact habit, characteristics
required for a nut tree’s ability to supply
calcium to the nuts.”
When trees receive standard nitrogen,
reduced root growth and focus on apical
shoot growth can create a huge calcium
sink at the top of the tree, diverting
calcium from blooms and nuts.
The second technology, LoCal, uses a
naturally occurring compound to mimic
the effect of auxin, allowing plants to
properly absorb calcium where they
would normally have a low ability to do
so. “Cell Power® Calcium Gold and Cell
Power® Calcium Platinum both use
LoCal technology to supply nuts with
calcium very effectively, ensuring good
nut fill and improving tolerance to disease
and molds,” says Francisco.
He recommends almond growers start
with Cell Power® SizeN® Ca, applied as
a dormant spray — 1% solution to soak
bark — one to four weeks before budbreak.
“Four follow up applications of
Cell Power® SizeN®, through drip, will
help keep roots alive, maintain a good
shape and create the conditions for
high nut yield.”
Meanwhile, applications of Cell Power®
Calcium Gold and Cell Power® Calcium
Platinum are best started at flowering.
“Apply at 1 pint/acre, then top up after
two weeks with a final one ahead of
harvest. This will reduce shell seal
breakdown and increase yield.”
Learn more at www.OMEXusa.com.
The product names and brands
referenced here are registered and
trademarks of OMEX® Agrifluids, Inc.
© OMEX® Agrifluids, Inc. 2021.