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Qs for Darren - keyline plow - swales in keyline  RSS feed

 
Sam Boisseau
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Location: PNW, British Columbia
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Hi Darren,

I own the first two chapters of your upcoming book, great work! Are you still aiming to publish end of 2015? Also excited for the Polyfaces doc.

Questions:

1) Official keyline/yeomans plow are not easy to come by in America, or are expensive to import. What are the alternatives if we want to do some keyline plowing?

I read somewhere that you can use a chisel plow, but that this means a different things depending on the continent. How can I know that I have the right tool?

What are the drawbacks of using an alternative to the yeoman plow? Can you still adjust the depth for example?


2) How would you integrate Permaculture swales to a keyline design? Assuming that the swale is on contour or slightly off contour (e.g. Mark Shepard does 1% grade swales IIRC). How do they integrate in the whole keyline geometry?



Thanks!

 
Darren J Doherty
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Location: Bendigo Region, Victoria, Australia
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Thanks Sam,

We're aiming to get the Regrarians Handbook completed before we start the 2016 World Tour next March. We'll see how we go!

1. P.A. Yeomans used a chisel plow for years and got great results — certainly if that was all you had and you followed Keyline Pattern Cultivation (KPC) principles then there's no reason why you couldn't too. That said using one of the multitude of subsoilers out there would give you a better result than the chisel, mainly due to the reduced surface disturbance. Most important thing to me is to following the KPC principles. That means following not just the pattern across the landscape but also getting your timing right (the fall is generally the best time) and being progressive with your depth.

2. I find it difficult to reconcile the use of swales into Keyline Design to be honest. The swale is largely redundant if for example you are using KPC properly. However to expand on this I'll paste what I wrote recently on the same topic on our Regrarians Facebook Group:

"...To me a swale is an infiltration trench – in the UK the swales that people like Capability Brown built were drainage systems – the permaculture venacular has come to them being ditches with uncompacted embankments on contour – the inspiration for this coming from US Corp of Engineers work across the USA which resulted in the terrace structures pretty well everywhere with a slope east of the Rockies, to very large structures in the arid south west — such as those Bill visits in the Drylands episode of 'Global Gardener'. Some people put a gradient on them, some do not.

However their primary function in the context of this thread is as an infiltration ditch that captures overland runoff. Secondary functions are to direct that runoff to dams.

In my opinion if there is such a thing as a 'Keyline Swale' then it would be a swale placed on the Keyline of a Primary Valley. Of course those who know #KeylineGeography would know that this, and the saddle above it, are the only places one could have an element with that description.

Of course this could be extended out to the adjacent Primary Ridges . Now as Keylines are never on the same elevation that would mean that you'd have a whole lot of ditches ending at the water divide line of the primary ridge – which would be a bit chaotic.

IF you were wanting madly to do such thing, then you would have to place the swale on a Keyline guideline. This is not so simple a task and to do properly you really should have a good contour map to start with so that you can place it effectively. Fig 2.29-2.30 (pp.102-103) of the #RegrariansHandbook outlines the process one could use. In my opinion only then would you have what could constitute a Keyline swale or other swales that would run parellel to this guideline. That being the case then I believe you could apply this moniker.

However if one were using the whole Keyline program, and Keyline is a whole system after all with a whole planning process, then you would find that having a swale per se would probably not give you the water-harvesting performance that a water conservation channel (the Keyline description) or gradient road structure would. If you landscape management is about it all infiltrating then you are going to battle to get much run off to fill your dams and having purposely absorbant ditches as your main vehicle for moving that water is going to be suboptimal. That is why in Keyline the water conservation channels are compacted and in most cases have a gradient..."


Cheers,

Darren J. Doherty

 
Kelly Smith
Posts: 720
Location: In a rain shadow - Fremont County, Southern CO
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thanks for the reply Darren.

i learned a new term "water conservation channel"

 
Darren J Doherty
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Location: Bendigo Region, Victoria, Australia
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Thanks for the note Kelly,

I have used the terms that P.A. Yeomans used to describe his water harvesting features. That is the following:

Water Diversion Channel
Water Irrigation Channel
Water Conservation Channel

Cheers, Darren

 
Sam Boisseau
Posts: 155
Location: PNW, British Columbia
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Thanks Darren; I have a follow up question:

I'm assuming you cap the gradient of water channels? I remember PA Yeoman suggesting 1/200.

If so, how do you integrate those channels within the keyline geometry?

The issue I have here is that you might put in a channel with 1/200 gradient, but that the keyline geometry might have a gradient of 5%. I've seen this happen when you take for example a ridge guideline and go up the slope with equidistant lines.

So basically we're back to my original question but with channels instead of pemaculture swales. I guess this could also apply to an on contour driveway.

So how do you integrate on-contour or slightly off contour elements such as swales/channels/roads to a keyline geometry which has steeper guidelines/alleys etc?
 
Darren J Doherty
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Location: Bendigo Region, Victoria, Australia
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Good question Sam,

1. A channel of 1:200 would only be in highly porous ground – such as many granites — generally we go between 1:300-400 with our water conservation channels or gradient roads for catchment purposes. We do go to 1:100 on kerb and channelled roads when we have other features that need to run at the same gradient and therefore at an equidistant offset from that road — this particularly applies to stormwater and sewer pipes, the latter having a standard gradient of between 1:80 and 1:120.

2. With regards managing channels with Keyline Geometry — you'll very unlikely have a complete match there, however as compared with contour plowing you will have equidistance and the default fall to ridge in the system in between any lines above and below. The same applies if you have a contour swale above and below — you can still run Keyline Pattern Cultivation (KPC) oriented rows or plowing lines in between these, only you will have some areas above and below this KPC-treated area that won't match up.

3. I don't see any reason why you would do a road on contour — it would only serve to potentially undermine the road stability — of course we build roads on dam walls however we typically have 1m + of distance between the saturation zone and full water level and the top of the road. Most road gutters are not 1m below the road surface. If you are stuck on building a road on contour then you'll be investing in plumbing to get rid of the water that would otherwise saturate the road base and cause the outcomes that follow reaching liquid limits.

4. I'm not completely sure on this question however what I would say is that there is are gradients of both row fall and trajectory which one will establish according to each site. That said I am very satisfied that the outcomes in most cases of proper KPC is that even at quite steep gradients, runoff is severly mitigated even in some of the biggest events and rolling rainfalls. With regard row trajectory every implement has a comfortable turning radius and operating angle of slope. Find these all out, see what you're comfortable with, do some testing and off you go.

Thanks and all the best,

Darren
 
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