Narad (Richard Eggenberger)
Mon, 29 Sep 2008 17:14:29 PDT

In Rodale's 1978 Encyclopedia of Organic Gardening he writes to  

"Glauconite greensand or greensand marl is an iron potassium silicate  
that imparts a green color to the minerals in which it occurs.  Being  
an undersea deposit, greensand contains traces of many if not all the  
elements which occur in seawater.  It has been used for more than a  
hundred years and is a fine source of potash.

Greensand is commonly called a glauconite potash mineral, because it  
contains from 5 t0 6 percent of available potash.  The best deposits  
contain, in addition to the potash, 50 percent silica, 18 to 23  
percent magnesia, small amounts of lime and phosphoric acid, and  
traces of 30 or more other elements, most of which are important in  
the nutrition of the higher plants.

Factors underlying the immediate response of grasses to greensand seem  
to be greensand's ability to absorb and hold large amounts of water in  
the surface layer of the soil where the plant roots feed and to slowly  
release, over a long period of time, the potassium to stimulate  
photosynthesis.  In addition it contains the trace elements which may  
be deficient in the soil or in the surface layer of the soil in which  
the grass roots feed.

Greensand is so fine that it may be used in its natural form with no  
processing except drying if the material is to pass through a  
fertilizer drill.  An application consists of about 1/4 pound of  
greensand per square foot of soil, but you may want to spread it  
thinner.  It may be applied at any time spring or fall without danger  
of injuring plants, but , since greensand contains aluminum, do not  
over apply.  It may be applied on the surface in sheet composting, or  
used in the compost heap to stimulate bacterial action and enrich the  

Hope this may be of some use.

Richard Eggenberger (Narad)

On 29, Sep 2008, at 6:44 PM, Dell Sherk wrote:

> Hi all,
> I would like to know about the wisdom of using greensand in potting  
> mixes or
> as a top dressing as a source of potassium and trace minerals. I  
> read that
> it weathers quickly making the various minerals easily available to  
> plants.
> I have used it in the vegetable garden for some years, especially on  
> root
> crops, with success that cannot be directly related to greensand. I  
> think
> that it is a good, "kind" source of potassium, but I am wondering to  
> what
> extent the trace elements are available.
> Dell, in SE Pennsylvania, USA, Zone 6/7
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