[Scpg] steep permaculture slope ideas?

[Dan Hemenway]

Clay soils can turn to Jello when saturated.  Stability depends in part on rock content and in part, as has been suggested, on vegetation.  In the Phillipines and in Catalonia (Spain) I had the opportunity to see road cuts next to pines native to each region, exposing the roots.  They were like giant push pins, except that as you looked down the powerful and long tap-root, every few feet roots radiated out horizontally in whorls, so the tree was both holding the soil in place and pinning it deep, probably to bedrock.  In Luzon (Philippines), where the forest has  been cut for charcoal (by people displaced from the land, trying to feed their families), soil was sliding off the mountains in sheets.  This was a cascading catastrophe, reaching out into the coral reefs and harming everything between.  But I digress.


My thought is that the most responsible action would be to establish trees and maybe tap-rooted shrubs such as mesquite. (You don't give much in the way of climatic clues.)  If you want food, try drought tolerant species such as carob, maybe olive, etc.  But have those push-pin trees in place first.  If you don't know what to do, I strongly advise against shaping the earth.  You just don't have the experience.  I wouldn't try it without an expert consultant, and I've been practicing and teaching permaculture for 30 years around the world.  If the slope is already carrying the amount of trees suitable to rainfall, you might very gradually replace them with trees and tap-rooted shrubs more useful to you (or your client, it that is the case. Again, no info.) Whatever your do, do not install swales on the slope!  They will concentrate water and blow out and create erosion gullies.  Do not install swales anywhere near the crown of the slope, if you have control of that also (no info), as well, or any other water catchment system.  The slope is too steep and clay is too erodable.  If you decide on terraces, which I strongly advise against, have them slope gently away from the hillside, so that they shed water.  (This is advice I received from Willem Smuts, a geologist and permaculturist who knows a lot about these matters.)  Grade them precisely, keeping them exactly on the contour around the hillside, but as I said, with an exceedingly slight slope.  That way, they do not saturate in a rain, or at least are far less likely to saturate than a level terrace or, absolutely the worst in this cases, a terrace with a berm or an inward slope.


Sometimes, it is best not to mess with things, because whatever we do may cause problems.  This is the case with efforts to try to control watercourses.  And I think it is probably the case with your steep slope. Good luck. 


Dan Hemenway
Barking Frogs Permaculture





-----Original Message-----
From: Owen Dell <owen at owendell.com>
To: Kevin Gleason <kevin at kevingleasonart.com>
Cc: Wesley Roe and Santa Barbara Permaculture Network <lakinroe at silcom.com>; scpg at arashi.com
Sent: Fri, Sep 3, 2010 7:03 pm
Subject: Re: [Scpg] steep permaculture slope ideas?


First, check with a consulting geologist about whether your slope is stable 
enough to accept the destabilization and additional water loading that comes 
with terracing. I've seen too many incredibly expensive disasters resulting from 
inappropriate slope modifications to not speak up on this one.

Owen

Owen E. Dell, ASLA
Owen Dell & Associates
Landscape Architect • Educator • Author
P.O. Box 30433 • Santa Barbara, CA 93130
805 962-3253
owen at owendell.com
www.owendell.com


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rather do? ... It excites the hell out of me.” (Lawrence Halprin, Lovejoy 
Fountain, Portland, Oregon) 

On Sep 3, 2010, at 3:47 PM, Kevin Gleason wrote:

> Hi all,
> 
> I was wondering if anyone has good advice for creating a garden on a VERY 
steep slope (more than 45 degrees.)  I'd love some feedback on alternative 
terracing methods, whether this is too steep for small swales, good 
soil-holding, drought-tolerant  ground covers and other plants that would be 
useful and other ideas.  I remember hearing Brock Dolman talking about making 
retaining walls with burlap tubes filled with soil and a little cement.  Anybody 
tried it?
> 
> Thanks for your help!
> Kevin
> _______________________________________________
> Scpg mailing list
> Scpg at arashi.com
> https://www.arashi.com/mailman/listinfo.cgi/scpg

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