permaculture

[Toby Hemenway <toby@patternliteracy.com>]

On 2/1/06 2:42 PM, "Dylan Ford" <dford@suffolk.lib.ny.us> wrote:
 
> Why does everyone think that making alcohol from something necessarily
> excludes it from then being used for compost?

That's a good point, but it seems to me that the ethanol won't be made on
farm. Feedstocks will be transported to some central processing site (how
far, how much fuel?). Then the residue has to be trucked back to the farm
(more fuel) and paid for somehow. And then spread back on the field, (more
fuel). Plus, the paper I cited described about 40% of the ethanol coming
from forests; will that go back to the forest? If so, more energy there
(sprayed out of planes the way they fertilize forests now? Spray gunky
composty goo that will stick to trees and not reach soil, or do we mix it
with lots of water, increasing the weight?). That 6- or 8-to-1 ERoEI starts
to shrink a bit, much as I like the switchgrass idea.

> In fact I would not be surprised if what is lost
> as sugar is not made up for by the dead remains of the yeast that do the
> work.

I used to do industrial yeast fermentation. We always needed more nutrients
than the final weight of the yeast (we weighed it all), so it doesn't work
that way. Unlike plants, yeast don't get their carbon from the air, but from
sugars and other solids. Ethanol will mean a loss of some weight from the
feedstock, equal roughly to the weight of the ethanol.

> Also, enzymes that break down cellulose will speed the transition of
> many of these things back into available fertility.

Yep, although the soil organisms that depend on cellulose might be
disappointed in their loss of a food source (I'm just being picky here, I
know; return of any carbon source is better than none).

> The worms that turn organic material into high-value plant food must wait
> until bacteria, molds, fungi, yeasts, etc perform the initial decomposition
> anyway before they can consume it.

I fear you have this backward. Worms are usually the first to process
organic matter. I've watched them eat green leaf fragments. They take raw
detritus and grind it to paste (comminution).  The paste, with its great
increase in surface area, is then colonized by the worm's gut bacteria
(mainly cellulosic) which release nutrients into the worm's "intestine"
making the nutrients available to the worm. The resulting bacteria- and
organic matter-rich worm casts are prime sources of food for fungi,
protozoa, molds, and larger critters. (My source here is Ken Killam's "Soil
Ecology," which I checked to make sure there wasn't an enormous hole in my
understanding of soil ecology. If you can cite a source that makes me and
Killam wrong, I'll happily revise.)

Worms do ingest composted soil, but largely for its value as grit rather
than nutrition, since they lack teeth (like chickens) and need grit to turn
detritus into paste.

I just can't help worrying at this ethanol stuff; my training as a scientist
makes me look for holes. The idea is to then find a way to do it that has no
holes (or fewer). It's not for the sheer destructive fun of it. If we knock
the holes out of the ethanol story, it might have some use. I just wish
someone had knocked the holes out of say, building the interstate highway
system, instead of saying "Wow, we can go anywhere and it'll make lots of
money!"

Toby
www.patternliteracy.com