[NAFEX] leachey phos.

Alan Haigh alandhaigh at gmail.com
Fri Jun 26 13:02:39 EDT 2009

My limited understanding (I'm not in the business of rasing annual crops) is
that access to soluble P is particularly crucial in the early season
establishment of of annuals.  Once mychorizal relationships are established
there is often a less of a pressing need for supplementary soluble P.  I
think it was Elliot Coleman who stressed this in his first book, "The New
Organic Grower"- it was years ago I read it.

Have any of you diagnosed P deficiency in your fruit trees?  Cornell
routinely advises adding phosphorous when preparing an orchard site- even
when the soil contains reasonable amounts.  I wonder if concerns about P
deficiencies in fruit production aren't overblown.

I have heard of Hudson Valley growers who have taken heavy crops of apples
out of soils for 40 years without any supplemental P.  I know that in
ornamental arboriculture, phosphorous is considered rarely needed, at least
by my main guru in the field, Richard Harris.  He supports this position
with considerable research on tree responses to fertilzation.  Usually trees
only respond to N- even when their leaves are carted off every year.
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