Market Farming

[Brian <bcluton AT aol.com>]

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!

On Dec 2, 2011, at 8:36 AM, "Shoemaker, William H" <wshoemak AT illinois.edu> wrote:

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

---

From: market-farming-bounces AT lists.ibiblio.org [market-farming-bounces AT lists.ibiblio.org] on behalf of Road's End Farm [organic87 AT frontiernet.net]
Sent: Friday, December 02, 2011 7:11 AM
To: Market Farming
Subject: Re: [Market-farming] What is Rock Phosphate?

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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