permaculture

[Toby Hemenway <toby@patternliteracy.com>]

Paul Cereghino wrote:

> Second could be bioturbation... worms or other thingies pulling woody
> material down into the soil creating local low N spots?
That's a likely one--carbon moving down rather than N moving up. Thanks!

> It seems like there is a 
> need to align your mulch approach and your target community composition. 
I think so, too. Elaine Ingham and others have done a lot of work 
showing that non-woody plants (veggies, grasses) live in and prefer 
bacterially dominated soils, and those can be created using mulches and 
composts from non-woody tissue. (makes sense, yes?) Tree crops prefer 
fungal-dominated soils, which derive from woody tissue. Fungi are much 
better at breaking down wood than bacteria.

I use a lot of woody mulches simply because wood is a readily available 
resource here--the timber industry, but more locally, city arborists and 
the electric company generate tons of it for free. I try to get fresh 
stuff with lots of green leaves and young green twigs in it to give me a 
lot of nitrogen and so it will start composting quickly. I hypothesize, 
or maybe just delude myself, that with more green stuff in it, more 
bacteria will grow than in straight woody mulch, and thus help my 
vegetables. This year I've got a lot of straw leftover from a straw/clay 
sauna and heated cob bench we built, so I'll see if there is a 
difference due to the different mulches.

And I agree with Dieter, Keith, and all that the mulch does start 
decomposing almost instantly, with lots of critters moving back and 
forth between soil and mulch. You don't see hyphae in the mulch right 
off, but it doesn't take long before you do. And as William Albrecht 
says, "microbes dine at the first table," so there's probably a period  
after decomposition starts where N in the mulch is cylcing among the 
soil life and not really getting to the plants until the soil life 
settles down a bit.

Toby
http://patternliteracy.com