<table border=0 cellpadding=2 cellspacing="0"><tr><td>
<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








**************************************************
Post message: OliveOil@yahoogroups.com
Subscribe: OliveOil-subscribe@yahoogroups.com
Unsubscribe: OliveOil-unsubscribe@yahoogroups.com
Moderators: OliveOil-owner@yahoogroups.com
**************************************************
SPONSOR: http://www.sadoun.com
Yahoo! Groups Links
</pre>
</td></tr></table>

<table border=0 cellpadding=2 cellspacing="0"><tr><td>
<pre>G'day Mike
Sorry I didn't reply quickly, I've been at field days for a couple of days.
Yes the soil pH, texture and water content do have effects on Boron in the
soil. Calcium levels are in general relative to pH. There are variations
relating to exchangeable cation ratios of Potassium, Sodium and Magnesium
but just keeping it simple Boron and Calcium are closely related, and as you
know, have a very important role in Olive production. Boron will bind to
the soil and takes a long time to be used by plants. It is very immobile
but can be move through the profile with enough water. Soil texture changes
the level of boron required to cause toxicity. If the boron is highly bound
i.e. clay soil and the clay soil has a high nutrient capacity, much higher
levels of boron can be found in this soil with little effect on the plants
compared to a lighter sandy soil. Improving calcium levels in the soil is
always important when dealing with boron because of the interaction between
the 2.

I could rattle on for hours about nutrient interactions but I just tend to
get complicated. Mulders exchange chart is a good guide to assess basic
interactions of nutrients. Soil chemistry of each element helps us
understand the exchangeability or activity of individual nutrients. But the
most difficult part to follow is the interactions and chemistry of
combinations of nutrients within the plant. Specifically transport methods.

I always follow a procedure of steps when addressing soil conditions for
Olives and stone fruit crops.
REPARATION
Firstly pH (Soil interactions are based on chemical natures and require
specific soil pH levels to interact in a balanced manner)
Hence calcium, Potassium sodium and magnesium ratios (relative to soil
texture.)
Phosphorous, Nitrogen
Finally trace element levels
MAINTENANCE
Specific application of macro and trace elements with specific timing based
on growth stage.

This is never set in concrete as specific nutrient deficiencies or
toxicities may be so significant that they require immediate attention.

I hope what I've written is understandable, discussion of ideas and
experience can help.

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

>Russell,

>Is the uptake of boron from the soil affected by pH; soil type (clay /
>sandy, etc); ground cover or the amount of available water? I was using
>Borax which was about (from memory) 30% boron, spread widely over the root
>zone. The trees are mulched with sugar cane mulch and irrigated with 35L/hr
>sprays, the soil is a medium clay loam with a pH of about 5.5/6 and we have
>famously dry winters so the soil was bone dry other than from the
>irrigation.

Regards,

Mike Wilson.
Hunter Valley.







**************************************************
Post message: OliveOil@yahoogroups.com
Subscribe: OliveOil-subscribe@yahoogroups.com
Unsubscribe: OliveOil-unsubscribe@yahoogroups.com
Moderators: OliveOil-owner@yahoogroups.com
**************************************************
SPONSOR: http://www.sadoun.com
Yahoo! Groups Links
</pre>
</td></tr></table>