Re: [compost_tea] Re: C:N

From: Ted Peterson <ted.peterson_at_tcsn.net>
Date: Mon, 20 Dec 2004 22:38:02 -0800


Compost occurs naturally.
In nature, on a forest floor, there is no such thing as 131 dF for a sustai=
ned period.
Yet, material composts on a forest floor.
Leaves and debris break down and eventually form a humus.
Whole branches eventually break down through the actions of fungi.
There is no massive generation of heat as is one of the mainstays of compos=
ting in piles or windrows.
What does the heat do?
Heat breaks down material faster.
Heat destroys pathogens.
Heat destroys some undesirable seeds and keeps them from germination or cau=
ses premature germination and almost instant death from (you guessed it) to=
o much heat.
Too much heat carbonizes the material and makes it generally useless as a b=
enefit.
How do we get heat?
Thermal bacteria.
How do we promote thermal bacteria?
Nitrogen.
How do we get Nitrogen?
Animal feces, chemicals and certain grasses and grain meals.
How much Nitrogen do we need?
We need enough to feed the thermal bacteria and break down the Carbon. Thi=
s is called the C:N ratio. Most materials have a higher C than N.
Do we have to have heat?
If we want to compost in under "natural" times which is like a forest floor=
.
Can we cold compost and not use heat in some way?
Yes. The Leubecks (sp) in Austria have done a lot of experimenting with col=
d compost.
How do they get the Nitrogen and how do they control temperatures?
They get the N traditionally and use much smaller windrows or piles. They =
turn more often and instead of trying to get high temps, regulate CO2. (By =
the way, they produce probably the best compost in the world.)
Can we produce good compost without high temperatures?
Yes but we generally need a longer time. If we want compost fast, we need =
Nitrogen.

So think about what you want to do. You can produce purely green compost b=
ut in a commercial application or unless you move at a glacial speed, you w=
ill need to do something to boost the temps, regulate CO2 (you can artifica=
lly supply CO2 and O2 to your pile. You can add chemical or organic source=
s of N.) use starter compost or some other means to speed the process.

There are countless tables of C:N ratios and lots of suggestions for compos=
ting. Get a book or take a course. Look online: Just type in C:N ratio an=
d start surfing through the 100,000+ references. Type in composting and su=
rf through another 100K+ references.

Start a program where you try a bunch of different ways of composting in sm=
all areas. Change things and add things and track what happens. If you do=
n't have room to compost, get commercial compost. If it comes in plastic b=
ags, leave it in a pile and water and turn it and add a few things to it fr=
om your garden before you use it. Brew some tea with it and put the tea on=
to the compost before you use it in your garden or in your plants.

Ted Peterson
SOE

  ----- Original Message -----
  From: soilfoodweb_at_aol.com
  To: compost_tea_at_yahoogroups.com
  Sent: Monday, December 20, 2004 9:19 PM
  Subject: Re: [compost_tea] Re: C:N


  Hi Kirk -

  I just don't ever percieve myself as being a scary or intimidating person=
, so its hard for me to see why anyone would have any trepidation working w=
ith me. I suppose as people get older they just don't see that they move i=
nto the "silverback" category.

  I don't think of myself in that category. I'm just not that old!

  Oh, wait. Ah......

  just remember that in everyone's mind, you never age past twenty-somethin=
g. When I hit 100 years old, I might finally consider thinking of myself a=
s over 30.

  Anyway, I try to be approachable. I certainly can do stupid things, as d=
oes everyone else I know. There is always something we can chuckle about w=
ith everyone......

  Anyway, back to compost ----
  -------------------------
  Elaine from yesterday:
  If you alter starting materials, what do you suppose the effect will be o=
n C:N?

  Kirk:
  Precisely why I approached this with trepidation - I knew I wouldn't have=
 all the answers to questions you'd ask :-)

  Elaine today:
  The reason I put my first reply in question form is that I don't have all=
 the answers either, but there is a principle here that you want to think a=
bout and start building into your gestalt about compost.

  Think of compost as being built on the basis of three general classes of =
materials.

  Hi N, green and woody. Yes, high N is genernally green, but if it is hig=
h N, then it goes in that category, regardless fo greeness. You alter the =
mix of these three categories of materials in order to achieve temperature,=
 physical aeration and microorganism growth. More woody materials, more fu=
ngal food, more fungi. The more high N, the higher the temp will go (ok, a=
ssuming no toxic matrerials come with).

  The more woody, the wider the C:N. If you let if go anaerobic, and reall=
y blow off ammonia, the wider the C:N.

  Elaine from yesterday:
> If you compost with fungi predominant, where so much less C will be blo=
wn off as carbon dioxide, what do you suppose the effect will be on C:N?

  Kirk:
  Higher C:N. This might be Composting 101 but how do you compost with fun=
gi predominant and achieve temp?

  Elaine from today:
  Enough hi N to get high temperatures. Once fungi get growing, they too g=
enerate temperature.

  Elaine from yesterday:
> What would lead you to expect that all compost, regardless of starting =
materials, or way the composting process has been handled, has to finish up=
 at the same composition, and at the same C:N ratio?

  Kirk:
  Convention. Everyone who seemed to know has said 10-15:1. But I'm getti=
ng some understanding of why only one of the books I have suggested a "fini=
shed" C:N...

  Elaine from today:
  Bingo!!!!! I am so glad when people start catching on! I am NOT being s=
arcastic here. I can be told something, in ten different ways, sometimes, =
and I still don't get it, until, suddenly, bingo! A light bulb finally com=
pletes a circuit.

  Then I feel dumb, for not having caught on, flipped the switch, whatever,=
 for so long. Take home message here is, don't feel dumb. You managed to =
make the connection, something that even the most touted Ph.D.'s haven't ma=
naged, after working their whole career with bacteria.

  Elaine yesterday:
> If you allow the compost pile to become anaerobic, and most of your ava=
ilable N is volatilized, what will be the effect on C:N?

  Kirk:
  Higher C:N.

  Elaine today:
  Yep.

  Elaine yesterday:
> What is in compost that could greatly alter C:N ratio of the final prod=
uct? What is the C:N of bacteria, versus fungi? What kind of metabolites =
are produced? What is the difference in the way bacteria versus fungi use =
C?

  Kirk:
  I know bacteria are low C:N (~5:1) and fungi higher (20:1+), so I'm getti=
ng how a higher fungal content could get to a higher C:N. Protozoa, etc, a=
re even higher, so I can see how a good compost could have a high C:N. I h=
ave no solid ideas on last two questions.

  Elaine today:
  Bacteria blow off, on average, 60% of the carbon they use as CO2. Fungi =
blow off only 20% as CO2. So, you see the difference?

  Elaine yesterday:
> What is the difference in anaerobic versus aerobic use of N, and C?

  Kirk:
  I have absolutely no idea, but I know in anaerobic digestion a lot of C i=
s volatized off as methane, CH4..

  Elaine today:
  In anaerobic conditions, much less C is lost than in aerobic decompositio=
n. The ratio of bacteria to fungi have to be looked at as well, something =
we haven't really gotten around to yet.

  Kirk:
  Couple questions...

  Does this mean that a C:N of 10-12 indicates a bacterial-dominated compos=
t and that a C:N of 30 in compost that's "finished" - i.e., it doesn't heat=
 more than a few degrees on turning and respiration is low - is
  fungal-dominated? That may be obvious but I want to be clear(er:).

  Elaine today:
  Haven't seen that. Part of what you have thought through is correct - ba=
cterial-dominated compost is probably always in the C:N 10 - 12 range, as l=
ong as it didn't go anaoerbic. Then we see the C:N 20 to 30, which is what=
 I thought I was talking about the other day in my e-mail. Or more correct=
ly, that what I think I was talking about. Grin, my memory.....

  In fungal composts, when properly finished, C:N can range from 10 to 20. =
 I think it has more to do with the kinds of fungi, which means we have mor=
e work to do.....

  Kirk:
  There's been an interesting sub-thread here of using "young" compost for =
tea. Not sure what the theory is. It would likely be more "active" but te=
a-making or soil application normally activates critters that aren't dead. =
 
  Maybe someone could expound?

  Elaine today:
  When compost isn't quite finished, but has gone through the WHOLE heating=
 process and temps are falling below 100 F, the organisms are still active,=
 and thus will get into rapid reproductive mode much more rapidly. This is=
 discussed in the Compost Tea Brewing Manual.

  Kirk:
  Question I want to get to bringing that up is this: Is C:N changed in th=
e compost "maturation" process. "Finished" compost can be distinguished fr=
om "mature" compost - young compost being finished but not mature, presumab=
ly.
  Does the C:N of compost change much during the aging process?

  Elaine:
  Depends on the organisms predominant in the composting process. The grea=
ter the bacterial component, the more CO2 is lost, and the more N is concen=
trated in bacterial biomass and waste products. The greater the fungal com=
ponent, the more carbon remains, and the more other micronutrients remain a=
s well.

  Kirk:
  What's the difference between "young" compost and "mature" compost?

  Elaine:
  I think of young versus mature compost as relative activity of the bacter=
ial and fungal populations. When young, the organisms are still rapidly gr=
owing, generating temperature, and thus activity is high - above 10%.

  Mature compost means the organisms are not growing rapidly, not generatin=
g lots of temeprature, and not all that active - less than 10% activity. =
 

  Kirk:
  As I noodle through the murk of my books and memory here, I'm getting the=
 impression that C:N is only important on the front end of composting, not =
the result, except as a potential indicator of B:F ratios? Is this
  something that should have been obvious all along? Eeek!

  Elaine:
  You need to design the starting materials right, but I use the Cornell Co=
mposting Handbook to give me a general idea of the likely C:N of the mixes =
I put together. I use the actual temperature generated as the way to tell =
me if my guesses about how much chicken manure was actually in the chicken =
litter I bought, for example. I adjust the pile within the first 2 to 3 da=
ys if my guess proves wrong. The final C:N ratio - which takes weeks to ge=
t back many times - tells me B:F ratio - which takes a couple minutes if I =
do the qualitative method, or a few days if I send to the SFI lab.

  So, what is really most useful as a measure? Start using the little micr=
oscopes.....

  Have fun! See you Wednesday!

  --
  Elaine Ingham
  President, Soil Foodweb Inc.
  SFI Corvallis, OR
  SFI Port Jefferson, NY
  SFI Lismore, NSW, Australia
  SFI Cambridge, New Zealand
  SFI Culiacan, Mexico
  SFI Jerome, Idaho
  SFI South Africa
  http://www.soilfoodweb.com


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Received on Tue Dec 21 2004 - 06:58:03 EST

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