I have a couple of yards of compost from the last few
years of composting my leaves. The two years ago pile
now has a nice fine texture, and I decided, on a whim,
to check its pH. I came up with a somewhat alkaline reading,
say 7.0-7.5, which may be due to my use of a lot of leaves
(e.g. of polar and elm) that some sources demean for their
I gather that this level of alkalinity is more than most
veggies and small fruits want, especially in my context
(high plains of Colorado) in which acid soil is not an
issue. I'm wondering:
1) Is it reasonable to think that my compost might be
alkaline enough to account for the poor performance
my veggies have had in recent years (I typically
plant my veggies in furrows with a few inches of
my finished compost)?
2) If I want to acidify the compost, what might anyone
recommend? Obviously, elemental sulfur is a common choice,
as for blueberries, but I understand that many veggies
taste better if grown in low sulfur soils, so I have been
thinking to avoid that. I was thinking about
dousing my compost pile with some HCl (muriatic acid)
commonly available for masonry, scale removal, etc. at
a level enough to bring the pH down to say 6.0 or so,
but I wonder whether plants would be happy with the
chloride that would contribute to the soil.
As you can see, I'm not adverse to chemical solutions,
although I would be interested in softer ways to acidify
the compost as well. (Large supplies of oak leaves are
not something I can get my hands on.) So, thoughts and
suggestions would be welcome.
Mike Lacy, Ft Collins CO 80523
7.0 for leaf mold is not unheard of. My leaf mold, mixed with manure,
grass clippings and kitchen scraps. checked at 6.5 both times I tested
it. Now, both of us probably have measurement errors in the 0.5 range
(these color methods are soo unaccurate), so our composts may very well
be the same pH.
I also disagree that the alkalinity you have is too high. Beets, onions
and chard will like it exactly so, and I find the taste of tomato and
lettuce to be improved by alkaline shots of wood ash. Various brassicas
and some mustards will be better at 7 than at 6.5. Garlic, peas or
chicory will not care. Zucs, potatoes, beans and peppers do like it
more acid, and of course all berries except blackberries like it acid.
Finally, different composts definitely have different pH. If you want
acid, make compost out of wood chips. When I cover an area with them, I
only get sheep sorrel (a acid-loving weed) for two years in that spot,
and I have acid soil, but even the other acid loving weeds don't make
it in one-year old wood chips, so I am guessing that the pH must be 5
Tree companies will bring them to you by the truckload for free. I
never put them in my garden without adding a few pounds of wood ash.
They take a while to decay, but while they last they provide a great
mulch. They have little N, but good amounts of P and K, and so for
tomatoes they are ideal in every respect except pH.
il 28 Jan 2005 14:08:56 -0800, "simy1" ha scritto:
I've read on a site in Queensland that peppers like it slightly
alkaline. And figs also like it alkaline, so much so that some people
put concrete fragments in the bottom of the pot. Mushroom compost is
alkaline and if not sterilised , a source of mushrooms later. :-))
(unfortunateluy I can't locate the URL)
Loki [ Brevity is the soul of wit. W.Shakespeare ]
Leave it alone. Compost buffers ph irregularities and youyd be surpised how
well plants adapt to variances. I garden in soil with a PH of 8-8.5 and grow
everything imaginable. I do use lots of compost to buffer the ph. Id love to
have the "problem" of a soil ph of 7.0 Muriatic acid sounds like way over
kill. Sulphur takes a long time to work (applied 150 lbs this spring). Try
using aluminum sulfate ( not Ammonium!). This will lower it quickly, but I
still think your compost is fine, remeber its also not stable...it is
decomposing. As a better solution, add peat. Peat is acidic.
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