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<pre>> 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.
>

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.
</pre>
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