|
I agree, this is fascinating reading. I have occasionally heard of
folks adding rock powders of various types to their compost piles, then
spreading the compost on the fields. I'd be curious to know if this would
provider the needed biological activity, such that the elements in that
rock powder would be more available. I'd also be curious to know whether
there's been much academic research on the subject. A cursory stroll
through the top Google search results for "rock powder fertilizer" yielded a
wikipedia entry and page listings from commercial fertlilizer websites.
I'd have more confidence in the commercial claims if I saw them backed up
by similar results from the world of academia.
Kathryn Kerby, geologically challenged
frogchorusfarm.com
Snohomish, WA
Ruminations - essays on the farming life at
frogchorusfarm.com/weblog.html
In a message dated 12/2/2011 6:07:51 A.M. Pacific Standard Time,
wshoemak AT illinois.edu writes:
Well, clearly that was better than "rocks at the hedgerow"! Thanks Brian,
good coverage.
And good point about bioavailability. Rock phosphate is pretty slow to
become bioavailable too, which is why commercial ag treats it with acid to
make triple-super phosphate, making it more immediately useful to crops. But,
if you're growing organically, you should be stimulating the biological
community of your soil such that it imitates that process in a more regulated
manner, meaning your crops can have their phosphorus and eat it too.
Good stuff, even if a little expensive.
Bill
William H. Shoemaker
University of Illinois, Crop Sciences
St Charles Horticulture Research Center
535 Randall Road, St Charles, IL 60174
630-584-7254, wshoemak AT illinois.edu
From: market-farming-bounces AT lists.ibiblio.org
[market-farming-bounces AT lists.ibiblio.org] on behalf of Brian
[bcluton AT aol.com]
Sent: Friday, December 02, 2011 7:59
AM
To: Market Farming
Cc: Market
Farming
Subject: Re: [Market-farming] What is Rock
Phosphate?
Greensand is actually derived primarily from sedimentary ocean deposits
that are rich in Glauconite which is an Iron Potassium silicate and thus lends
the green color. It is ultimately a weathered sedimentary formation and
not a metamorphic rock such as granite that has undergone chemical and
structural changes associated with temperature and pressure. Thus you can see
various degrees of crystallization in granites depending on the mineral
origins, depth of deformation, cooling period, etc. Granites tend to be
EXTREMELY slow weathering which is part of the reason that we have old and big
granitic mountains like the Adirondacks in NY. I only mention this because of
the whole bioavailability thing again. There is very low nutrient mobility
and/or nutrient holding capacity in granite based rocks. Obviously the smaller
the particle size the better but even still they are chemically locked
up.
Brian
the guy with a geology degree that has used it primarily to throw rocks
into the hedge row!
I think the organic potassium fertilizer "Greensand" is derived from
granite. I bought some a long time ago but maybe my memory is too fuzzy. But
that is the only granite based fertilizer I'm aware of.
Rock phosphate is mined from central Florida, which has some of the
worlds most important phosphorus reverves. Rock phosphate is simply mined
and ground up. I can't remember the analysis but I'd guess its about 24% P.
I agree with Rivka. Until you find out what they used in the drilling
process, I'd avoid using it on the asparagus beds.
Bill
William H. Shoemaker
University of Illinois, Crop Sciences
St Charles Horticulture Research Center
535 Randall Road, St Charles, IL 60174
630-584-7254, wshoemak AT illinois.edu
I don't think there's usually much phosphate in granite; though will
defer to geologists or soil scientists on this.
I would also strongly recommend asking the well driller whether
anything used in the drilling process might be mixed with the rock
grindings, and if so what the material is. I don't know whether they use
lubricants etc.; presumably anything used is either nontoxic or in some
manner prevented from getting into the well, but I'd want to find out which
before putting the grindings on the beds.
Before assuming that your particular asparagus beds need phosphate, I'd
get a soil test. In some areas this nutrient is naturally high; and in some
other areas, some gardens and fields are high in it due to years of historic
excess applications.
-- Rivka; Finger Lakes NY, Zone 5 mostly
Fresh-market organic produce, small scale
On Dec 1, 2011, at 11:48 PM, Thomas P Hurtgen wrote:
Can the rock grindings from well drilling be used
on vegetable and flower beds? I read that asparagus in particular
benefits from an application of rock phosphate. Would grindings from
well drilling be a substitute for bags of rock phosphate from the local
supplier? The well driller has said that most of the rock is a type
of granite. Thanks much for any help/advice offered
Thomas P
Hurtgen
(7b)
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