Compost Making FAQ - Part 6
Article: 48877 of rec.gardens
Subject: Re: Making Compost FAQ (long)
Date: Sun, 4 Dec 1994 01:52:57 GMT
The following is ADDITIONAL composting advice from Jim McNelly,
aka Mr. Compost, which has turned up. If anyone has other of
his posts saved, I would sure like to receive them.
Michael Matthews in central VA
Subject: Advanced Composting
TJ>I have enjoyed your messages on composting over the last
>year or so. Thanks for livening up my day with some
>particularly interesting questions and have, in fact, had a
>"compost" pile since last fall. I'm using one of those black
>plastic sheets with large holes (3" >dia?) which is formed
>into a cylinder with no top or bottom.
I am trying out one of the "green plastic sheets" with smaller
holes. I believe that you have a "Presto" Bin, or some
reasonable facsimile. My guess is that it is kind of floppy,
but stable when full.
TJ>My first compost pile got hot (over 120 F), and occasionally
>I can get it hot again after trimming a bunch of trees. But
>normally it is acting more like a "worm box" than a compost
You better not be casting aspersions upon my worm buddies. Did
you add any redworms, they move up from the underground, or you
just making a cool composting observation?
>The bulk of the input is from the leaves from bottlebrush
>trees and kitchen scraps (fruit and vegetable material).
Bottle brush leaves! I remember growing up in California, how
the hummingbirds love the flowers. You must have quite a
collection if you get enough material to fill a composting pile.
>I would like to create a hot pile more often, though I am
>reasonably happy with cold decomposition. But, I have some
Hot piles are a lot like baking bread. It is nice to know how
to do it, but not necessarily something you want to do all the
TJ>I have seen copies of the lists put out by various people
>concerning the nitrogen/carbon ratio of various materials,
>i.e. leaves, grasses, etc. My question is, comparing a leaf
>from a bottlebrush that I pick and which is green in color,
>with one that dries up and turns brown and then falls to the
>ground, or a trimming that falls to the ground and laying
>there eventually turns brown, does the ratio change? That
>is, when a leaf goes from the color green to the color brown
>does it lose nitrogen and thus change from a "green" material
>to a "brown" material?
This is an excellent question, and has been the source of many
a debate among us professional composters, long into the
evening at composting conferences, sampling the local ale from
the microbrewery..... But I digress. Yes, one man's green
stuff is another man's brown. In my and other composting gurus
attempts to "make composting simple", we refer to the "green
and brown" metaphor. But as you point out, it does not hold up
so well under scientific or real world scrutiny. Many greens
actually browns and vice versa.
An example is that thatch from lawns is considered "brown"
matter, and so is yellow straw. Orange carrot peals or pulp
are "green" and black sludge is also "green". I have composted
"brown" soy hulls that heated like the beans themselves, which
are brown but are called "green". Many brown leaves heat like
green matter, and I have even got hot composting from bark
The point is that mixing green and brown is good advice for
composting 101, for beginners. It is mostly designed to
suggest mixing brown leaves with green grass.
The goal of "getting a pile to heat" is largely a misconception
of what is taking place in a composting pile, a belief that
heat itself is causing the reaction. In my various commercial
operations, one common question from visitors is "where or how
do we 'add' the heat?" Another common backyard question is
whether or not to put the pile in the sun or shade. Since heat
is generated *by* the composting process, it is a byproduct,
not a cause.
Adding heat or any organic matter will not cause significant
decomposition. A pile in the sun may absorb some radiant
sunlight, and this may help in the spring, winter or fall if
the pile is hovering above 40F.
Heat in and of itself is a sign of composting, not a cause.
Piles, being self insulating, hold heat. An unaerated pile may
be hot, but that does not mean that it is active. It might
just mean that it is well insulated so it holds what little
heat is being generated. Along the same lines, a cool pile may
be quite active if the heat is being removed through aeration
or convection. The best advantage of a hot pile is that it
helps kill diseases and weed seeds. I see little advantage
over cool composing in terms of compost quality. A hot pile
may decompose more quickly, but when was "fast" made into the
important decision criteria?
Is a fast campfire "better" than a slow one? Is smoking meat
"better" than a fast hot grill? For commercial operations, I
look at the heat *removed* as the measure of composting rate,
not of heat itself. It is like the home hot water heater. The
water heats quickly and energy is consumed. The insulation
holds the heat at the desired high temperature. But the actual
energy used is not indicated by the temperature of the water,
but by the gallons of hot water consumed.
So, in a very round about way, I care little anymore about
mixing green with brown in commercial operations, because I
know that some greens may behave like browns and vice versa,
and I can usually get either to compost just fine in any state,
mixed or not. If I am looking to conserve nitrogen, then I
want to compost the green (high nitrogen) material as quickly
as possible in order to effect nitrogen stabilization before
the N is lost to the air or water, usually as ammonia.
But I have shocked many of my fellow professionals by
composting all high nitrogen materials or all brown materials,
or equally well with a mix of some sort. Some materials may be
hard to get started, like sparklers at the fourth of July, but
again like sparklers, once you have one going, it is easier to
get the next one going.
So yes, there is a point where green stuff becomes brown, and
yes leaves and green matter lose nitrogen in stockpiling. But
nitrogen is not the most important issue in composting, nor is
heat generation. So I say stick with what whatever works to
make dark crumbly humus soil like stuff with the amount of
space and effort *you* have available. Don't let the raw
materials or the composting books dictate what you should or
I do know that keeping organic matter moist is critical, and
that adding a bit of old compost helps, whether hot or cold.
Fork freely and often!
Granite Connection 612-259-0801
* June 27th - Auntie Em: Hate you. Hate Kansas. Took the Dog
Compost Making FAQ - Part 7
Subject: Blood Meal and Compost
HK> One of my compost piles is mostly dead grass, leaves, and
HK> weeds. It was going pretty good but then after a month or
HK> so, it just lost its oomph (sp?).
A good batch of compost is *supposed* to lose its "oomph" after
about a month or so. It is not like a campfire where the wood
oxidizes down to ash in a short time. Biological oxidation is
determined by the fate of microbes; not a chemical formula.
Raw organic matter has both volatile and non-volatile solids.
The non- volatile fraction includes ash, minerals, glass,
rocks, metals, and other non degradable components. Even a rich
organic matter source like peat might contain 10% to 20% inert
matter. Many manures may be as low as 50% organic matter,
especially if they are scraped off soils.
The composting process is considered "complete" if there has
been a 40% volatile solids reduction. When about 20% has been
reduced, it is increasingly difficult for the pile to generate
heat, since most of the "volatile" fuel has already been
oxidized. Of the organic (volatile) solids, much is in the form
of lignin and cellulose (wood). This fraction, while organic,
is not as "volatile" biologically speaking as are
carbohydrates, sugars, and proteins which decompose quickly.
These materials take longer to decompose biologically, so may
be why your pile has "slowed down".
On top of these complex interactions between microbes, fungi,
actinomycedes and organic raw materials, the byproducts of
decomposition, particularly humic compounds, are in and of
themselves slow to decompose and oxidize. Humus, the most
stable form of organic matter in the soil, may last for years
and years without further breakdown.
So adding fresh matter like blood meal may cause a sudden burst
of decomposition activity, sort of like adding lighter fluid to
cool charcoal briquettes, but don't expect the rest of the
matter to suddenly spring into ignition and decompose.
My rule of thumb, if you truly desire active, hot compost, is
to make piles in batches, mixing and moistening thoroughly
*before* putting the stuff into a bin. Then let the pile cook
for three or so weeks, maybe with a turning or two. Hot
composting is also helped by passive aeration from the base,
rather than the sides.
For a pile that seems to have cooled prematurely, mix 50% with
fresh green material like grass clippings to get it to re-cook.
I believe that you will find this plan more effective than
dosing it with blood meal.
HK>Anyway, I figured that it was lacking nutrients so I
>sprinkled a half cup or more of blood meal in there. What do
>you think? Will it help? Oh yeah, my compost bins are of the
>poor man variety (a chickewire cylinder). Actually, them work
>remarkably well. They take a little longer than the wood or
>plastic boxes, but with my limited amount of plant refuse,
>they are perfect. Regards, Howard Knight
* RM 1.3 * Eval Day 12 * When a ball dreams, it dreams of
being a frisbee
Granite City Connection (612) 259-0801
Email: email@example.com (Jim Mcnelly)