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<pre>G'day

The rates of Boron mentioned from the information I have appear extreme.
Soil level of Boron for olives should be between 2 and 3 ppm. Basically
that's 3 kg of actual Boron per hectare. A very narrow range indeed and
foliar levels between 30 and 100.
Variations is sample results are common because of seasonal fluctuations of
born levels due to demand i.e fruit and flowering. Soil assessment can be
very hit and miss because of the small amounts in the soil and previous
applications.
Boron toxicity can be disastrous when excessive Boron is applied as it takes
years for the boron to deplete. Trees can have minor symptoms expressed but
have serious infertility issues resulting in low yield. Always apply boron
with care as reapplication is always better that boron toxicity.
Foliar application can be safer than soil application as the rate applied is
very low and can be distributed more evenly across the area. Uneven
application can result in toxicity in localised areas.
500 grams per trees is about 120 to 150 kg per hectare. 40 to 50 kg actual
boron depending on product. Bulk phosphate fertilisers are applied at this
rate not trace elements. I generally recommend chelated boron at very low
rates applied as a foliar pre-flowering and mid season. We often have to
apply foliar products for pests and disease, so why not combine specific
nutrients if required to save time.

I hope I haven't opened a can of worms, but the more we throw ideas and
knowledge around the more we'll learn.

Cheers
Russell March
B. Ag. Sc.
Agronomist & Technical Sales Consultant.

-----Original Message-----
From: OliveOil@yahoogroups.com [mailto:OliveOil@yahoogroups.com] On Behalf
Of Steven Chaffer
Sent: Thursday, 8 September 2005 8:56 PM
To: OliveOil@yahoogroups.com
Subject: [OliveOil] Boron deficiency

My last independent soil test revelealed a slight Boron deficiency.
Based on the recommendations in the report I calculated that the
amount of Borax my soil required was 5 g per sqaure metre.

I seem to remember the last time I flicked through the Olive
Production Manual they were recommending adding 500 g per tree in
similar circumstances. I think I also read the same figure in a
report from a group of growers in the Hunter Valley in here in
Australia.

500g seems like a hell of a lot of Borax. I was under the
impression that Boron has a very small range between effectiveness
and toxicity.

At the same time I do want to make an meaningful difference to my
soil Boron levels as my trees do drift in an out of Boron deficiency
when I do a leaf test. I have used Solubor foliar sprays as a short
term remedy.

Cheers,


Steven Chaffer
Kaoota Tasmania








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