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permaculture - Re: [permaculture] Long term sources of available Iron...

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  • From: Meg Mullett <meg@kcnet.com>
  • To: permaculture@lists.ibiblio.org
  • Subject: Re: [permaculture] Long term sources of available Iron...
  • Date: Fri, 17 Oct 2003 08:10:50 -0500

Hi David,

The only really long term solution to making more iron available to your
plants is to lower the pH of your soil. There probably is enough iron
available in your soil, (a good soil test can tell you), but when the
soil is too alkaline iron, zinc, manganese and copper (as well as some
other nutrients) become "locked up" so the plants are unable to take
them up. Which is also why you've had some success with foliar
feeding. The plants are able to take a small amount of those nutrients
in through their stomata.

Sulfur products (ammonium sulfate, sulfur coated urea, iron sulfate,
flowers of sulfur, aluminum sulfate) are often added to alkaline soils
to help lower pH. Although large amounts are often needed, and the
decision as to which product to use will be base on your particular soil
type and consistency. You will not want to add sulfur to your gardens
while there are crops in there because the basic reaction of most of
these products with water is to create sulfuric acid, which will burn up
your plants.

Carbon dioxide from decomposing organic matter and root respiration is a
great acidifier of soils, so as someone else already recommended, I
would also suggest incorporating large amounts of any kind of organic
matter your can get your hands on into the soil, and laying it on top as
mulch. This can be done while crops are in the ground. - Just don't
till up your growing plants' roots.

Perhaps you will need to use a combination of the two. Apply sulfur in
the off season, as well as organic matter, till it in and let is rest a
while. Then plant your crops and continue with lots of organic mulches.

No matter what you do, - barring complete removal and replacement of
your soil, you will likely always have a slightly alkaline soil, so I
would also suggest choosing your plant material with that in mind.
Opting for plants that prefer or at least tolerate alkaline soil will
ease your work load alot.

Here are some links to help understanding about soil pH and nutrient
availability as well as some recommendations for amendments and rates:

http://www.sustland.umn.edu/implement/soil_ph.html

http://en.wikipedia.org/wiki/Soil_pH

http://hubcap.clemson.edu/~blpprt/lowerpH.html

http://www.colostate.edu/Depts/CoopExt/TRA/PLANTS/alksoil.html

http://hort.ifas.ufl.edu/gt/soilph/soilph.htm

http://ag.arizona.edu/pubs/garden/mg/soils/ph.html

Hope this helps,

Meg in KS

PS - DON'T use the wood ashes! That will raise your pH, not lower it.



> To: permaculture@lists.ibiblio.org
> Subject: [permaculture] Long term sources of available Iron...
>
> Hi,
> I have a calcareous soil substrate here in the Bahamas (pH 8.1) and
> have an iron deficiency in many of my plants. I do have an organic
> micronutrient spray, but applications have to happen every two weeks.
> Plants have been responding well to this, but I would like to think up
> some alternatives. Does anyone know of any long term solutions to making
> iron available to plants other than applying chelated iron?
>
> Also, wondering if folks have heard of wood ashes lowering pH?
>
> Thanks, David
>
> David Orgain
> The Island School, Bahamas
> 242-359-7625
> www.islandschool.org




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