Stump dirt and mushroom compost
I
consider stump
dirt to be a miracle
planting aid. But what is it?
The obvious answer is
--- that moist, dark, earthy-smelling organic matter found inside
decaying trees or logs. Different trees create stump dirt of
varying quality; my favorite source by far is our ancient hollow beech
halfway up
the hillside, while box-elders product lower grade stump dirt.
Maybe hardwood stump dirt is better than softwood?
The analytical side of
me started nibbling away at what stump dirt actually is a few weeks
ago, and the best idea I've come up with is that stump dirt is pure
organic matter created when fungi decompose wood. The closest
mainstream garden ingredient I could find is mushroom compost, but that
is the result of fungi growing on higher nitrogen substrates like straw
and manure, so any comparisons should be taken with a grain of
salt. One study of mainstream mushroom compost showed that it
consisted of:
- 28% organic matter and 58% moisture
- 1.12% nitrogen, 0.67% phosphate, and 1.24% potatssium (aka NPK of
1.12-0.67-1.24)
- 2.29% calcium, 0.35% magnesium, and 1.07% iron
- C:N ratio of 13:1
Naysayers on the internet
report much lower NPK values for mushroom compost, though --- closer to
0.7-0.3-0.3 --- and I suspect our stump dirt is at the lower end of the
fertilizing spectrum. That would explain why the garden beds I
treated with stump dirt last year didn't show much growth --- stump
dirt isn't a replacement for compost. Instead, it makes a great
ready-made potting soil and can also be used like peat moss to fluff up
organic-matter-poor soil. If we ever had enough to apply stump
dirt to our garden in large quantities, I suspect it would act a bit
like biochar, providing spots for
microorganisms to grow unhindered. And stump dirt from
deep-rooted forest trees is probably even higher in micronutrients than the analysis above
portrays.
All of that said, you
can't buy stump dirt, and you only find it in middle-aged to old
forests. I mine a couple of five gallon buckets every year out of
our beech tree, but save it for extra-special occasions. Another
reason to have a mature woodlot on your property, perhaps?
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About us: Anna Hess and Mark Hamilton spent over a decade living self-sufficiently in the mountains of Virginia before moving north to start over from scratch in the foothills of Ohio. They've experimented with permaculture, no-till gardening, trailersteading, home-based microbusinesses and much more, writing about their adventures in both blogs and books.
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