WCN_Dec17WEB

NUTRIENT APPLICATIONS
AT ALMOND BLOOM
By Kathy Coatney | Editor
Nitrogen is an extremely important
nutrient in almond production,
but research suggests that there isn’t
any value in applying it when almond
trees are dormant, according to David
Doll, University of California Cooperative
Extension, pomology farm advisor
for Merced County.
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“Applying nitrogen during this period
increases your risk of leaching and
a loss of the nitrogen from the system,
which is essentially throwing your money
away,” Doll said.
“Even if you exclude the negative
environmental effects, there’s not much
value to the plant and it will lead to
poor nitrogen use efficiency due to the
risk of leaching below the root zone,”
Doll said.
After the trees leaf
out, then it’s time to
apply the nitrogen, Doll
said.
Potassium
Potassium is another
important nutrient
for almonds, and soil
reports should be
reviewed to determine
need and application
strategy, Doll said.
“People should review
their soil reports.
There is a value called
the cation exchange
capacity (CEC),
and which indicates
how many positively
charged ions that can
be held in a certain
quantity of soil. And
if that value is under
10 milliequivalents
per 100 grams of soil,”
Doll said, that indicates
sandier soils.
For growers who have very sandy
soils (e.g. sand or loamy sand), they may
want to consider applying potassium in
January and February, Doll said.
“In these cases the soil actually
doesn’t hold onto potassium very well,
leading to the possibility of leaching if
too much rain comes in after the application,”
Doll said.
“By shifting that application a little
bit later, the farmer can hedge their bet
that they’ll get enough rain to push it
into the rootzone, but there won’t probably
be enough rain to leach it out of the
root zone,” Doll said.
Most of the sandier soils are in the
northern San Joaquin Valley, but there
are some very sandy areas that stretch
from San Joaquin County all the way to
Kern County, Doll said.
“If you’re on a heavier type soil,
potassium can be applied to the fields
at a relatively high rate in order to help
get that into the soil and into the root
zone,” Doll said, adding applications
are typically done between October and
December in heavier soils, then the rain
carries it in.
Unless the soil report is indicating
differently, growers should be trying
to replace the potassium that they’re
removing, Doll said.
“And with potassium that’s roughly
92 pounds of potassium oxide or K20
for every 1,000 kernel pounds harvested,”
Doll said.
20 West Coast Nut December 2017