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Re: Organic matter's effect on soil bulk?
In article <masimoDz8EKw.Iyr@netcom.com> masimo@netcom.com (Michael Maas) delayed the second coming by announcing:
>I have an area about 50'x100' that is leveled out mine tailings from
>hydraulic mining. The soil is long gone, washed down the river in the
>late 1800s. What is left is about 15 to 20' of rock. Someone pushed the
>rock out into a flattened plateau in the past but little grows there.
>
>I have been thinking of what I might start dumping on this area to build
>up an organic/soil base so that it might eventually sustain plants. Chips
>from the local tree trimmers are available, as well as straw/hay and the
>red clay that is abundant in the locality. Good loam or even good topsoil
>is more rare and more expensive.
>
>Given these materials what might one do to build up a base into which
>plants could be placed and expected to survive and prosper? What plants
>might themselves be used and what chemical amendments might be added to
>aid the decomposition process?
It depends on what you want to grow in the area and what your time-frame
is.
If you are looking to restore the area with native plants in a hurry, the
best way might be to bring in a lot of the kind of soil that native
plants live in, which sounds like red clay in your area. Native plants
in native soil would probably be your best chance for permanent success,
especially if you let nature take its course and go through the succession
process from grass -> forest.
If you are looking to raise vegetables or flowers in a hurry, a mix of
clay, sharp sand, and compost would be a good way to go. You can get a
soil test from your county extension agent which will tell you what
kind of amendments the soil needs.
If you don't have compost, you can make it out of the wood chips, straw/hay,
and other organic materials, or you might be able to get some from your
local landfill at a reasonable price. (It would be quite a bit of
effort to make enough compost for 5000 square feet of bare rock, but
I'm sure you'd have an amazing sense of satisfaction when you are done :) ).
Alternatively you could just heap whatever organic materials you can
get right on the rocks and let nature manage the decomposition.
In my opinion the best way to speed the decomposition is to mix in
lots of high-nitrogen organic material rather than chemical amendments.
You may not feel the same way. The best way I have found to get lots
of free high-nitrogen material is to ask for horse manure from local
stables or horse owners. Usually they are happy to all you to haul away
truck loads for free. This really speeds up the decomposition of the
wood chips and straw.
If you have more time on your hands you should consider bringing in
whatever soil and organic matter you can find, mixing it, and planting
cover crops for a couple of seasons. The idea here is that you plant
something fast-growing and good for the soil and turn it under before it
goes to seed. It decomposes and adds organic matter to the soil which
improves structure and water-holding characteristics. Examples include
annual ryegrass, buckwheat, and clover. These are sometimes called
"green manure" crops. After a couple of seasons of this, the soil should
be in pretty good shape and ready for whatever you want to plant there.
I believe that Golden Gate Park in San Francisco was created through a
similar process, although they started with sand rather than rocks.
Someone found a series of plantings that turned the area from sand into
a loam that can support very large trees. Of course this took a long,
long time. You might be able to track down additional information on this
and get some good ideas.
One last thing--and this is important. If your rocks are near a
river or stream (you mentioned hydraulic mining) you should consult
with a professional before taking the advice of some guy on Usenet. It
would be a Bad Thing if you inadvertently wound up putting a lot of
concentrated soil amendments, fertilizers, or even dust into a stream
or river, since that can screw up the fish situation and other things
as well.
I'm a gardener facing a similar situation, not a farmer or a soil
scientist, so don't take what I say as gospel. At any rate, what
you are considering is a really good thing, and if you decide to go
through with it I'd love to hear periodic updates. (I'm reading from
rec.gardens).
Regards,
Gozer@oro.net
--
Washing one's hands of the conflict between the powerful and the powerless
means to side with the powerful, not to be neutral. -Paulo Freire
PGP email welcome.
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