Subject: low pH soil ... resistant to lime?

From: [email-masked] (Frank Miles)
Date: 13 Mar 1995 20:53:38 GMT

We have tested our soil for about 5 years now (Sudbury kit), only to
find a persistent low pH: initially about 4.5, it has crept up to 
under 5.5.  This is despite adding over 100 lb of dolomitic lime each
year to our 800 ft^2 of garden soil (this would seem to be a pretty
high concentration).

What might be the problem?
	- the lime might be leached out in each winter's rain (we're
			in Seattle).
	- lime doesn't change pH as well as you might think (tell me
			more).
	- the Sudbury kit is inaccurate
	- there's something in the soil that persists in decreasing the
			ph.  (perhaps our compost pile?  the breakdown
			of the sod pile, what used to be the top layer
			of our garden plot?)

Has anyone had a similar experience?  We know that most garden plants
really don't like this low a pH (hard for the roots to absorb the right
things when there's such an exchange occurring just due to pH).

TIA...			-frank

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From: [email-masked] (Allyn Weaks)
Date: Mon, 13 Mar 1995 19:52:34 -0800

> things when there's such an exchange occurring just due to pH).

Most Pacific Northwest soils have little clay, and leaching of all
nutrients is fairly quick, with the result that they are naturally
infertile(*) and low pH.  You might reduce the leaching somewhat by
increasing the organic content a lot (if you haven't already) to buffer
any pH swings.  A good healthy soil with plenty of decomposers (fungi,
insects, worms, bacteria, even (gasp!) slugs) and a heavy mulch layer to
give them plenty to work with is even more important here than back east
to keep the nutrient cycle going.  Some cover crops (buckwheat?) do better
than others at grabbing calcium and other pH raising ions to prevent them
vanishing over winter.  Dandelions and other deeply taprooted plants are
good at bringing up calcium and other goodies from the subsoil if said
goodies haven't washed away altogether, so don't poison them - pull them
up and utilize their little corpses!  And certainly grow a winter cover
crop or keep a deep mulch layer rather than let the soil be bare.  Mulch
is available free from tree trimming companies, though they may bring you
ground up conifers, which won't help raise your pH :-)

[(*) One of several reasons to disbelieve the logging companies when they
claim that they can continuously grow trees here on a 50 year cycle, slash
burning in between.  The nutrient cycle can't support it.]

To minimize toil and trouble, you could switch to native plants for as
much as possible of your yard, and only try to keep a small area at a
higher pH for exotics and veggies (though my lettuces and beans and such
did just fine last year in 5.5).  The book by Kruckeberg, _Gardening with
Native Plants of the PNW_ is a good place to start looking into the lovely
native possibilities - not only a wide range of flowering shrubs (many
with tasty berries for you and the birds) and ground covers and ferns, but
wonderful lilies and irises and lots of perennials.  If you choose things
that are happy in the local dry forest and clearing areas, you get the
added bonus of not having to water more than once or twice during the
summer once they become established.

My pH is at about 5.0 to 5.5, and I need to reduce it somewhat to make
life easy for huckleberries and to get rid of that nasty grass I've got
all over the place :-)  My moss is coming along nicely in the back yard,
and I'll probably put in wild strawberry and kinnikinnik as ground cover
in the front, which faces south and gets a fair amount of sun in season...
-- 
Allyn Weaks
[email-masked]