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Compost constituents

  • Subject: [cg] Compost constituents
  • From: Don Boekelheide dboekelheide@yahoo.com
  • Date: Thu, 29 Dec 2005 12:29:53 -0800 (PST)

Hi, Sharon,

I notice that most of the posts you are getting back
are about the carbon-nitrogen ratios of compost
feedstocks, rather than the plant nutrient value of
finished composts made from different materials, which
I think is what you may be looking for?

The 30:1 C:N ratio, beloved of composters, is a rough
generalization based largely on the work of Dr.
Clarence Golueke in California, who worked with
composting as a sewage (aka biosolids) management tool
as much as a horticultural resource. That ratio is
important for getting a pile to heat up efficiently to
high enough temperatures to destroy or suppress
pathogens. So, those C:N ratios can be useful in
mixing materials so your pile heats up (though - like
most everything in gardening and ecology - it is a
system, and you need to mind moisture, availability of
oxygen, particle size and the list goes on. Meanwhile,
out in the woods, as the bumper sticker says, "compost
happens". At the end of the process, btw, the C:N
ratio is typically more like 10:1.

The rule of thumb, and my experience agrees, is that
composts are, broadly speaking, 'unifinal' systems
that end up quite similar when the process is
finished, regardless of materials they are originally
made from. Also, composts are generally not rich
enough in any specific nutrient (including N) to be
considered a 'fertilizer' in the NPK sense (unless you
supplement the pile by adding, say, rock phosphate to
bring up P levels - but I usually do that in the
garden beds, not the compost pile).

Nevertheless, compost is garden gold. Why?
Oversimplifying, it adds stabilized organic matter in
a highly beneficial form to garden soils, and, more
important possibly, it adds beneficial organisms to
build a stronger soil ecosystem.

A few qualifiers:

"Compost" is a word with multiple meanings - in the
UK, it still can mean "potting soil" (for instance,
John Innes composts - check out
http://theseedsite.co.uk/innes.html). Likewise, here,
community gardeners are wise to be very careful about
composted biosolids contaminated with industrial
(heavy metals, nasty organics) wastes. This is a
controversial area, and since it touches on (horrors!)
poop, power and plutocracy, our culture can't deal
with it rationally.

"To compost", the verb, is applied to a controlled,
human-managed decomposition process, regardless of
material decomposed. For example, you don't want to
use 'fresh' poultry manure, it will burn your plants
and stink to high heaven. Instead, you use 'composted'
manure, that has sat, usually in a pile, while the
microbes broke it down and stabilized it. So, yeah,
different manures certainly can contain different
nutrient profiles, and properly handled such manures
are, really, 'composts' in the American sense. There's
lots out there in the extension lit on nutrient
profiles of manures, though most focus on NPK rather
than other nutrients - for starters:

ttp://edis.ifas.ufl.edu/AA205 (poultry poop in
(livestock in Nebraska)
Rodale and ATTRA also have good info on this.

The most valuable thing about a well-made compost,
research indicates, may well be the richness of
beneficial micro-organisms it adds, rather than the
"CHOPKNS CaFe"* nutrient profile. In this sense, at
least 'fresh' but mature composts made from different
materials (for instance, wood chips vs. spoiled hay
vs. food scraps) can have contrasting microbial
profiles that may affect the plants in your garden.
For instance, wood-based composts tend to be fungally
dominated - and so may work best for crops and orchard
plants that prefer that type of soil ecology. The best
source of info on all this is, of course, Elaine
Ingham's www.soilfoodweb.com (go to the Oregon site to
read her newsletters). Ingham and company have moved
into compost tea brewing, which I'm not crazy about in
community gardening settings but it is interesting

Last thing, about N. Our local municipal compost can
have as much as 2% N (though only a percentage is
readily available to plants). Since compost gets
spread heavily (1-3 inches isn't uncommon, and it's
easy have "active" gardeners raid the pile brought for
a whole garden and quickly, with a wheelbarrow, pile 6
inches plus on their own bed). That big volume
introduces a lot of N into your soil, and you may not
see response to additional N fertilizer the year after
that kind of thing happens.

So, my suggestions would be, rather than trying to
make a 'super-compost' that has all 16 nutrients (is
it 18 now?) by blending different ingredients, make
'old fashioned' compost using solid methodology from
whatever stuff you have available (ideally for free).
Add it to your soil to add life and organic matter.
Then, correct specific nutrient problems by adding
specific materials rich in that material (ie, bone
meal for P and some N, etc) to your garden soil along
with the compost. And manage N by adding in measured
amounts throughout the growing season - don't try to
apply all needed N at once, even using compost or

But, Sharon, I know you're a good gardener from this
list, and do whatever you want. Making compost is fun
and endlessly fascinating - my current method is big
outdoor worm bins. That's what works for me (right

Good luck, keep us posted on what you do and how it

Don B., Charlotte, NC/ Mecklenburg County PLANT
Program (home composting classes, ecological
landscaping, toxic waste reduction, Master Composter
program...among other things)

*CHOPKNS CaFe is the way generations of agronomy
students have managed to remember the main plant
nutrients - C, H, O, P, K, N, S, Ca and Fe. There are
sentences that cover the rest of 'em (used to be 16).
So where does a cabbage and a carrot go on a date? C.
Hopkins Cafe...

--- community_garden-admin@mallorn.com wrote:

> Send community_garden mailing list submissions to
> 	community_garden@mallorn.com
> To subscribe or unsubscribe via the web, visit
> or, via email, send a message with subject or body
> 'help' to
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> You can reach the person managing the list at
> 	community_garden-admin@mallorn.com
> When replying, please edit your Subject line so it
> is more specific than
> "Re: Contents of community_garden digest..."
> Today's Topics:
>   1. Re: Design and plans for Classic Indoor Garden
> (adam36055@aol.com)
>   2. FW: [cg] NPK values for various compost
> materials (gwenne.hayes-stewart@mobot.org)
>   3. FW: Harvey's garden (Betsy Johnson)
>   4. Re: FW: [cg] NPK values for various compost
> materials (Sandy Pernitz)
>   5. Re: FW: Harvey's garden (adam36055@aol.com)
>   6. RE: Harvey's Garden (Bailey, Sarah)
>   7. RE: RE: Harvey's Garden
> (gwenne.hayes-stewart@mobot.org)
>   8. Re:NPK values for various compost materials
> (jsbmh2@aol.com)
> --__--__--
> Message: 1
> Date: Wed, 28 Dec 2005 13:33:00 -0500
> From: adam36055@aol.com
> <002801c60b08$727e1fb0$c2aa72d8@gardens>
> Subject: Re: [cg] Design and plans for Classic
> Indoor Garden
> To: jimf@burlingtongardens.org,
> community_garden@mallorn.com
> Jim, 
> I love these. If I manage to get enough cash up to
> buy one for my apartment, I'll buy one. 
> Enough of an endorsement?
> Regards, 
> Adam Honigman 
> -----Original Message-----
> From: Jim Flint <jimf@burlingtongardens.org>
> To: community_garden@mallorn.com
> Sent: Tue, 27 Dec 2005 12:10:32 -0500
> Subject: [cg] Design and plans for Classic Indoor
> Garden
> Judy and all, 
> Thanks to everyone for the interesting dialogue on
> indoor gardening. 
> For the past few years, I've been working and
> testing a new design for a basic indoor garden for
> home and school use. 
> About 50 of these units are in use in Vermont with
> good results. 
> Now seems a good time to do a beta release of the
> design and plans, first to the ACGA list serv. 
> A photograph and detailed plans are available on our
> web site at the link below. 
> I'd appreciate any feedback from ACGA list serv
> members on the design. 
> The most important component is the light fixture
> and tubes, as this is the critical element for seed
> starting. It's possible to get by on the cheap with
> lights, but the investment in quality fixtures and
> light tubes is well worth a few extra dollars. 
> Happy New Year! 
> Jim Flint 
> Friends of Burlington Gardens 
> 33 Tracy Drive 
> Burlington, VT 05401 
> 802.658.5733 
> www.burlingtongardens.org 
> ----- Original Message ----- From: <Grow19@aol.com> 
> To: <community_garden@mallorn.com> 
> Sent: Friday, December 23, 2005 5:13 PM 
> Subject: [cg] do it yourself 'grow' lights 
> > thanks to everyone. i have shop lights on chains
> attached to beams in > the 
> > ceiling of the basement and grew a lot of
> seedlings last year. i was > hoping 
> > to find simple construction designs for a version
> to be used tabletop in 
> > schools. guess i can figure it out myself. 
> > Happy Holidays. 
> > judy 
> The American Community Gardening Association
> listserve is only one of ACGA's services to
> community gardeners. To learn more about the ACGA
> and to find out how to join, please go to
> http://www.communitygarden.org 
> To post an e-mail to the list:
> community_garden@mallorn.com 
> To subscribe, unsubscribe or change your
> subscription:
> --__--__--
> Message: 2
> From: Gwenne.Hayes-Stewart@mobot.org
> To: community_garden@mallorn.com
> Subject: FW: [cg] NPK values for various compost
> materials
> Date: Wed, 28 Dec 2005 14:57:03 -0600
> I asked our local authority, Chip Tynan answer guy
> for Missouri Botanical
> Garden so here are his ideas.  Gwenne
> -----Original Message-----
> From: Chip Tynan 
> Sent: Wednesday, December 28, 2005 2:53 PM
> To: 'gordonse@one.net'
> Cc: Gwenne Hayes-Stewart; Mara Redmon
> Subject: RE: [cg] NPK values for various compost
> materials
> The Science & Engineering section on the Cornell
> Composting webpages has a
> discussion of C/N ratios that includes links to the
> list in the publication
> "On-Farm Composting Handbook" with N and C/N values
> for many materials, as
> well as a link to a table of lignin that also
> includes N and Ash values.  It
> also provides formula to teach you how to calculate
> C/N values yourself
> http://compost.css.cornell.edu/calc/cn_ratio.html
> Klickitat County (Washington) has an interesting
> compost mix calculator with
> nutrient data and invites users to contribute data
> obtained from test
> samples they submit to the laboratory at Washington
> St. University, but the
> current list hasn't yet grown even as large as the
> Rodale '79 list
> =993887739&fCategoryIdSelected=948111261 
> Hope this helps!    Chip
> -----Original Message-----
> From: Gwenne Hayes-Stewart 
> Sent: Wednesday, December 28, 2005 9:22 AM
> To: Mara Redmon; Chip Tynan
> Subject: FW: [cg] NPK values for various compost
> materials
> Either of you guys have an answer to this?  Gwenne
> -----Original Message-----
> From: Sharon Gordon [mailto:gordonse@one.net]
> Sent: Tuesday, December 27, 2005 5:44 PM
> To: community_garden@mallorn.com
> Subject: [cg] NPK values for various compost
> materials
=== message truncated ===

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