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<pre>All great stuff and so true, Russell - a well constructed explanation. Just
don't forget to work with the soil biology as well. It is at least a third
of the total soil fertility.

Best regards,

Gerhard
-----Original Message-----
From: OliveOil@yahoogroups.com [mailto:OliveOil@yahoogroups.com] On Behalf
Of Mike Wilson
Sent: Friday, 16 September 2005 3:35 PM
To: OliveOil@yahoogroups.com
Subject: Re: [OliveOil] Boron deficiency

> 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

Thanks Russell, that is a weight off my mind. I had used the aforementioned
quite heavy rates of Borax on clay soils and was stressing about possible
toxicity, but it seems that I should be okay given that the soil is a fairly
hydrophobic clay and does not tend to take in rainwater all that well unless
we get a week of gentle soaking rain, and that happens quite rarely.
Normally we get the short, sharp dump (and associated run-off, erosion, etc)
and than have to rely on irrigation to actually get moisture down to the
root zone - normally 35 litre an hour sprays, but some drips.

We have added Calcium in the form of powdered gypsum, with the odd backup
spray of liquid lime & gypsum but this program is being looked at to improve
the effectiveness.

You mention "Mulders exchange chart" which I take it is a guide to mineral
uptake? Do you know where I can find such a chart?

Regards,

Mike Wilson.








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