permaculture

[<permed@nor.com.au>]

>>Would you permaculture experts and enthusiasts think these big tall trees
>>about 30' apart would be of any help amidst about 5-10 acres of vegetable
>>and herb and flower crops? Would some shade help with moisture containment
>>or am I 'barking up the wrong tree'? 
>>Johnny Gregory
>
>I would evaluate the shade VS the wind break you pick up with the trees 
>which can help veggie production.  In other words thin or prune to balance 
>the needs of your site.  These poplar won't last all that long, I would 
>start looking into replacements and get them planted sooner rather than 
>later.
>Mark
Beware of allelopathy with poplars....
I saw a poplar windbreak in New Zealand, there was a farm track between 
the trees and the farmers field  of sweet corn - the allelopathic impact 
of the poplars was the most dramatic visual example I've observed yet. 
Near the track germination was sparse and plants severely stunted (barely 
18 inches high), the density and plant size gradually and uniformly 
increased with increasing distance from the trees and at 1 and half times 
the hight of the poplars into the field the plants were dense, lush and 
over 6 foot high. The sunflower crop on the other side had exactly the 
same phenomena. It was interesting that the most stunted section was 
within the height of the plant horizontal section and plants rose in a 
J-curve to the 1.5xh point.
I'd be rather cautious to use poplars in a productive cropping system 
especially vegies. Poplars are fine in grasslands and agroforestry 
systems, don't have the same allelopathic relationship with grasses and 
clovers quite like growing under them.
Robyn