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Re: Organic matter's effect on soil bulk?



In response to my request for ideas on converting a large rocky flat
to soil that would support plants...

gozer@au.oro.net (Runs With Scissors) wrote:


>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.

Yes, this would be good. There are already some pine trees growing in
the rocks but little else.

>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.

Eventually I would probably want to landscape the area but  quite
likely with a mix of native plants and wildflowers.

>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 :) ).

Having just finished rototilling and planting about an acre of former
river bottom with the attendant rocks this kind of satisfaction is the
last thing I or my back is looking for!

>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.

Yup, this is right along the lines I was thinking of.  

>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 hadn't thought of this until you mentioned it despite the fact that
I have been planting legume mix and vetch in other areas on the
property.  

>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.

Thanks for the inspiration.

>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.

Not a problem. They're a long ways from the river right now.

>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.

Thanks for your useful comments.

Mike




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