permaculture

["John D'hondt" <dhondt@eircom.net>]

I find it a bit unusual that you talk only about nitrogen fixing plants 
Cory. I have alweays thought about nitrogen fixing bacteria for I have seen 
bacteria on their own without plants fix nitrogen. As long as they had a 
source of decomposing carbon and some supply of phosphate that is.
Also on our grazing fields we see a competition between clovers (mostly 
white clover because this stays quite low to the ground where other clovers 
grow higher and are eaten by ruminants a lot faster) and grasses. Grasses 
need nitrogen to do well and compete out the clover eventually. When we put 
some rock phosphate out the clovers boom again.

All that said, I know well that plant species provide nitrogen fixing 
bacteria with root exudates to make them thrive and do their business. But 
again, phosphate in the soil is essential for the nitrogen fixing process. 
(as are oxygenation of the soil and many trace elements) Nitrogen itself 
should never be a problem since there are about 8 metric tons of (inert) 
nitrogen gass pressing down on every single square meter of the planet.

Gleditshia triacanthos has never worked for us in Ireland. It grows well in 
a green house and dies in less than a year when transplanted outside. Maybe 
we have less than a regular temperate climate.
john

Just found this resource for nitro fixing fodder legumes, wonderful! 
http://www.fao.org/ag/AGP/AGPC/doc/Publicat/Gutt-shel/x5556e00.htm#Contents

Would love to hear back from people on experience with legumes in any 
climate similar to Florida - sugar sand soils, sometimes extreme wet/dry, 
temperatures hot, humid in summer, often freezing in winter (down to 15 
degrees or below in many areas). I am looking to plant many fast growing 
multi use legume trees and want to make sure I am picking the best 
varieties. Leucaena, gliricidia, sesbania, are considered "invasive" in 
Florida. I am trying to find info on less invasive cultivars (though I agree 
with Toby Hemenway's assessments on "opportunists" I hesitate to be the one 
to personally bring thousands of opportunist trees into this relatively 
delicate ecosystem). Leucaena lan (I believe this is lanceolata) is 
considered not invasive but I have not found any of this cultivar.

The native sweet acacia has gnarly thorns but is beautiful and works well 
where thorns are not a problem.

What experience do people have with the non nodulating nitro fixers like 
cassia, etc, as far as actually putting nitrogen into the soils? I have not 
used them enough to really know how they do.

On a different note, I'm still trying to determine the nitro fixing 
capabilities of gleditsia triacanthos in temperate climates.

Koreen Brennan

www.growpermaculture.com
www.facebook.com/growpermaculturenow
www.meetup.com/sustainable-urban-agriculture-coalition
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