permaculture

[Mark <mpludwig@facstaff.wisc.edu>]

At 10:23 AM 11/12/02 -0500, you wrote:
>   When googling "water harvesting" I found an African site which had lots of
> water catchment berms used for growing trees. I thought I'd adapt that
> concept in an easier way and create a diamond pattern on my sloping crop
> fields using the half V trencher instead of so many berms, like a cocked
> tic-tac-toe board or a giant piece of graph paper on a slight rotation off
> alignment with the slope. Thus we could plant all shade and orchard trees in
> the intersections and all extra unabsorbed water in that 'quadrant' would be
> channelled by the surrouding half V trenches directly to the trees, thus
> multiplying the use of rain- as if several times the rainfall had occurred.

This sound both excessively complex and possibly failure prone.  Unless I 
misunderstand you, these channels will all run down hill, and though you 
might think this will get more water to your trees, my guess is that it 
will actually hold less and will cause streams of water to meet at your 
trees and possibly wash them out.  The advantage of trenches or keylines on 
the contour is that the water stops there and can soak in rater than 
running down the hill, this cross hatch will not really halt the 
water.  Always keep in mind when working with runoff that you have to 
design for peak loads (referred to here as X year events, ie 10 year events 
happen once every 10 years on average).  What would your system look like 
if a serious thunderstorm took place?  How about a hurricane?  I can't 
imagine this would be much fun to mow either.  I also question wether water 
is such a limiting factor in your area to require extensive effort to 
conserve it, simple contours and efforts to build soil organic matter to 
hold water longer between rains may be quite sufficient.


This comment on poplars' longevity makes me wonder what other more permanent
trees could be suggested.?? I'd think some poplars would get 40-60 years old
or more. That should suffice fine for seasonal vegetable gardens. Permanence
is of course the best.

I would guess the life span to be about half that if our northern Quaking 
aspen is similar.



Mark P. Ludwig
Poultry Research Lab
University of Wisconsin -Madison
608-262-1730 WK
608-846-7125 HM