Hi Back in the spring I made a video about
planting blueberries, and because blueberries
like an acidic soil
I talked about various ways you can
bring down the pH of your gardening soil.
And one way I mentioned was to use pine
needle mulch.
Now, I heard back and in one of the comments from MrChipGardner
who has a YouTube channel as well, and he said actually pine needles don't bring
down the soil pH
and he gave me links to two sources: one
from Washington State University
and one from the Forest Industry Council and because this is quite different from
what I'd heard in the past
I decided as Stephen Legaree for his
thoughts on the topic
Stephen is not only a biologist but he
also has extensive experience working
with the Boreal forest in Canada
so I thought I'd ask Stephen to appear on
video today to answer some of my
questions about pine needles
and soil acidity.  So, to start off, Stephen,
do pine needles bring down the soil pH?
What a great question Patrick. So, I'm
standing here in the boreal forest
of Canada in order to answer your
question
Pine needles do not actually make soil
acidic. They are
themselves acidic however this is a
common
misconception. Even universities like Cornell University
makes reference to the fact that pine
needles cause acidity in soil
That's incorrect. Although the pine needles
themselves have a pH about 3.5, they
don't
decay and transfer that to the parent
material. By the time they are
decayed enough to transfer anything, they're at a neutral pH of 7.
Okay, but if pine needles don't
increase acidity, why is it that pine
forest soils are usually more acidic?
Well, that's very interesting question, Patrick. In fact,
You're correct.  The soils in
the Boreal forest are acidic, but it's
not because of the pine needles themselves.
The pine needles are acidic on the tree
but what happens is they fall to the
ground, and
they don't transfer that acidity at all.
Now,
the Boreal forest
characteristically has a
very large canopy.
What that canopy does it - it means not a
lot of this beautiful sunlight actually
makes it through.
So, we have a dense canopy, high volumes of rain also happen in this area,
which means we're limited in the in the
microbial activity that occurs within
the soils
and decomposition happens very very
slowly.
With the increased precipitation
and slow decomposition what happens is
the water moves through the column very
slowly.
A major feature here in the Boreal
forest is
bogs and fens, which are
characteristically defined as where
water either
stays or moves exceptionally slowly
through the system.
And as that water leaches through that
initial A horizon - so the organic on
top - what it does is it takes with it
a lot of I had the buffering
capacity of most soils.
In return, the longer that water stays in
contact
with the parent material below that it
releases
acidic elements, meaning that top organic
material
ends up being acidic, and it's not at
all due to the pine needles that 
that fall and decompose as part
of that.
what if I were to, say, mix the pine
needles into the soil and possibly speed
up the decomposition process?
Would that help with the transfer of the
acidity to the soil?
What a great question. Even if you
combined the
pine needles into the soil itself it
simply doesn't break down fast enough to
transfer any of that acidity
to the surrounding soils. Well that was
very interesting Stephen.
Thank you so much for taking your time
to share your expertise on this topic.
I think is something that's going to
generate some discussion, so i hope to
hear from viewers in the comment section
below as to what your thoughts are
on the topic of pine needles and soil
acidity. Well that's all for now.
Thank you very much for watching, and
until next time remember
you can change the world  one yard at a
time.
