Re: Protea and Iron
- To: m*@ucdavis.edu
- Subject: Re: Protea and Iron
- From: "* T* F* <f*@aloha.net>
- Date: Thu, 13 May 1999 14:38:40 -1000
>At 10:34 AM 5/13/99, John Atkinson wrote:
>>At 07:38 12/05/99 -0400, Xavier wrote:
>>
>>>I have no references readily at hand, but I have rarely read anything on
>>>Australian Proteaceae without the author mentioning the toxicity of
>>>phosphorus.
>
> I couldn't resist doing a little library research on this topic
>today at UC Berkeley. I looked into Hawaiian soils and into soil and
>nutritional requirements of Protea's. I found:
>
>a) Hawaiian rainfall is *very* variable, from as low as 30"/year to 70" in
>higher elevations of the big island and Oahu and, of course, over 200" on
200"+ is not uncommon down at the lower windward elevation in Hilo, HI
onthe big island. Hence it has the greatous rainfall of all USA cities.
MAX rainfall is over 400+ for Kauai and perhaps portions of the Hana
rainforest on Maui (I am told the gauge gets overloaded on the heavy years
and may actually be more). I need to check there is a manual of Hawaiian
Soils somewhere as well as NOAA info for Kula, Maui.
>Kauai. The texture is also diverse with clays, clay-loams, silts and
>sands. Under these circumstances I'd expect to find wide differences in pH
>even within one island. Unfortunately the Hawaiian soil surveys that I
>read said nothing of pH.
WE have a rather young (geological) fine, fluffy, clay soil, of
iron/alluminum oxide origin. Need to check pH. Seeing as out tap water is
very soft and acid, I would suspect that out soils are not as alkaline as I
suspected...
>
>c) the leading US soil text, by Brady, makes a passing reference to
>'elements that can--in excess--lead to deficiencies of minor nutrients'.
>Under iron Brady lists molybdenum, sulfur, manganese, zinc and.....ta
>da....phosphorus.
>
>d) most of the Univ. of Hawaii literature concerns the big money crops,
>sugarcane, beef, bananas, et.al. No mention is made in connection with any
>of these crops of P toxicities. Hawaiian farmers apparently routinely add
There is work on macadamia which are protea for most intents and purposes.
I was told (floriculture course at UHH) that they have the same proteated
roots, close to the surface and contining nodules that apparently are used
for phosphrus absorbtion. I have photos and a paper somewhere of the
research that demonstated the affects of 16 lbs per tree P applications on
Iron concentration in the newer tissues. So maybe what we see as iron
problems are all "phosphrus toxicity". Similarly, I do not see the
disorder on all of the plants. I suspect that each species/cultivar has
different tolerances to pH/phosphurs, etc. Perhaps that is why disorders
were not reported by the Israle groups findings.
> And, perhaps more significantly, these folks reported that *root
>hair initiation completely ceased on Protea's at pH's over 6.0*. They
>listed an 'ideal' pH for protea of 4.7 to 5.7. If that is correct I'd
>expect to see interveinal chlorosis at pH's in the mid 6's.
>
>Jerry Heverly, Oakland, CA
Mach T. Fukada
fukada@aloha.net
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