Re: acid-loving plants
- Subject: Re: [SG] acid-loving plants
- From: M* T*
- Date: Fri, 4 May 2001 17:03:28 -0400
Lynn, in answer to your question, I'm going to copy and paste a post
from Bob Stewart to Gardens-L that I saved from 1998. Bob is a very
knowledgeable Extension Agent and I thought this explained things
very well regarding lowering soil pH. I know Bob would not mind me
sharing his wisdom here.
"The alternation of soil pH for gardening purposes is accomplished
with two
sets of materials: calcium or magnesium for raising the pH and
sulfur for
lowering the pH. It important to also realize that the pH scale is
a log
scale, and the change of every full pH number is a ten fold change in
acidity/alkalinity.
The best material for lowing the pH is elemental sulfur;
however,
elemental sulfur must be broken down by microbial oxidation before it
has an
effect on the soil pH. The paradox is that these microorganisms that
breakdown
sulfur are not plentiful in soils where the pH is above 6.0.
Therefore a good
pH lowering program involves two steps: (1) an initial lowering of
the pH
using iron sulfate and (2) a maintenance of the lower pH by the
addition of
elemental sulfur. The increased microorganism population that
develops when
the pH is initially decreased will slowly break the elemental sulfur
down,
resulting in a long term pH decrease.
The amounts of iron sulfate or elemental sulfur to use depends on the
initial
pH, the texture of the soil, and the size of the area to be treated.
In
general, to lower the soil pH from 7.0 to 6.0 on a loam soil, add 5
pounds of
iron sulfate and 1.5 pounds of elemental sulfure per each 100 square
feet of
area. If the soil is sandy, decrease these amounts to 3 pounds of
iron
sulfate and 1 pound of elemental sulfur. Check the pH after two
months and if
not sufficiently decreased make another application of iron sulfate
(the amount
depending on the pH of the soil).
Aluminum sulfate is often sold for lowering soil pH but in general
it's best to
go with iron sulfate in order to avoid potential aluminum toxicity
problems."
Bob Stewart
. . . . . . . . .
Changing your native soil pH is more or less a lifetime project, not
one that you can do instantly nor that comes in a bag like your
customer wanted...loved that:-)
As Claire pointed out, rather depends on how much work a person is
willing to undertake to grow a plant not normally suited to the
prevailing conditions. If you fall in love with a plant, any amount
of effort seems worth it, but mostly I think it's better to try to
work with plants suited to what you have on offer.
Marge Talt, zone 7 Maryland
mtalt@clark.net
Editor: Gardening in Shade
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> From: Lynn Barbee <msgardens@HOTMAIL.COM>
> Date: Monday, April 30, 2001 9:23 AM
>
> What do you guys recommend as a way to amend alkaline soil? I had a
customer
> the other day who wanted to buy acid soil. I assume she thought it
was
> available in bags, but maybe she knows something I don't.
Miracle-Gro now
> has amended soil in bags, but I have never seen anything for
acid-loving
> plants. This is one of those gardening topics with lots of opinions
and ways
> of doing things. How many of you use sphagnum peat? What about
aluminum
> sulphate? Just plain old Mir-Acid, no soil ammendments? We live in
zone 5,
> NW Indiana. I don't think fertilizer alone will do the trick, but I
know
> some who do just that. Maybe the answer is, as our county extension
always
> likes to say, "It depends."
