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  • From: Steve Diver <steved AT ncat.org>
  • To: market-farming AT lists.ibiblio.org
  • Subject: [Market-farming] Alfalfa pellets for leaf-based compost bins
  • Date: Wed, 25 May 2005 16:42:30 -0500

Here are the details on alfalfa pellets as an easy-to-use
organic nitrogen source to balance C:N ratio for leaf-based
compost bins.

When you think of urban landscapes with heavy tree cover,
leaves are sometimes the primary compost feedstock
available to home composters. However, urban gardeners
rarely have access to dairy manure, poultry manure, horse
manure, and related organic nitrogen sources found on farms
as a means to balance the heavy carbon content found in
"leaves."

This resource pointer introduces the use of alfalfa pellets
to blend with leaf-bin compost piles, using 50-lb bags
of alfalfa pellets -- commonly sold as "rabbit pellets" at
local feed stores -- which are easy to get home in
the trunk of a car.

The orginal recipe calls for a 50-lb bag of alfalfa pellets
per 1 m3 leaf-filled compost bin.

Scoop-fulls of alfalfa pellets are scattered amongst the
leaves, along with water to moisten the leaves and alfalfa,
as the compost bin is being filled.

The nitrogen from alfalfa and the well-moistened feedstocks
provide the right conditions for indigenous microbes to
initiate decomposition and thermophilic heating
of the compost pile.

I've taught this technique to the Master Composter classes
in Washington County, Arkansas, and I've employed this
compost method myself with good results.

My introduction to this method came from Don Boekelheide,
home compost coordinator in Charlotte-Mecklenburg County,
North Carolina, on the old Compost-L discussion list.

This topic comes up now and again, so I've identified
the following web-based papers and educational training
materials from Don Boekelheide.

The item titled "Charlotte-Mecklenburg Hands-On Composting
Workshops and Home Composting Method: A Technical
Description" contains a detailed summary of the home
composting methods in Charlotte-Mecklenburg.

Much of this information is just as relevant for
smaller-scale market farms.

To balance the high carbon content of crispy-dry autumn
leaves, composters can use a "Budget" source of nitrogen
(commercial fertilizers like ammonium nitrate or urea) or
an "Organic" source of nitrogen (bagged cow manure or
bagged alfalfa pellets).

It turns out that the alfalfa pellets work very well as a
compost activator, they are easy to purchase at local feed
stores, and they are easy to transport in urban vehicles.

Don and I finally met a couple of years ago at a compost
tea workshop in Chatham County, NC.

Don explained they also get good results by using just
25-lbs of alfalfa pellets, whereas the original C:N
calculated recipe and compost demonstration projects
were based on one 50-lb bag of alfalfa pellets per
1 m3 leaf-filled compost bin.

Thus, gardeners and farmers can use these composting
guidelines with confidence, and they can adjust the
alfalfa to leaf-bin recipe according to local conditions.

Here are the web-based reference materials that
describe backyard composting in Charlotte-Mecklenburg
County, North Carolina.

A few excerpts are copied below to capture relevant details
on compost methodology and to provide helpful calculations,
figures, and "numbers."

An interesting figure was found in the section below
on "Compost Production." One m3 compost leaf bin
will result in sufficient finished compost to spread 1-inch
in depth over 97 sq. feet, which matches a 100 sq. ft.
biointensive vegetable bed.

Best regards,

Steve Diver
http://www.attra.ncat.org


+++++++++++++++++++++++++++++++++++++++++++++

PLANT - Piedmont Landsape and Naturescape Training
Charlotte & Mecklenburg County, North Carolina
http://www.charmeck.org/Departments/LUESA/Solid+Waste/PLANT+Program/Home.htm


Compost Book: Composting in the Piedmont
by Don Boekelheide
PLANT - Piedmont Landsape and Naturescape Training
http://www.charmeck.org/Departments/LUESA/Solid+Waste/PLANT+Program/Compost+Book.htm


Backyard Composting
PLANT - Piedmont Landsape and Naturescape Training
http://www.charmeck.org/Departments/LUESA/Solid+Waste/PLANT+Program/compbro.htm


The MCPLANT Master Composter Volunteer Program in Charlotte,
North Carolina: Stop Preaching to the Choir, Turn the Choir
into Missionaries
By Don Boekelheide and Ann Gill
Charlotte-Mecklenburg Waste Reduction
Charlotte, North Carolina
http://www.p2pays.org/ref/11/1015801.pdf
_____ 19-page PDF


Encouraging Home Composting the Hands-On Way:
Lessons from Charlotte-Mecklenburg
D.H. Boekelheide
Home Composting Program, Charlotte, NC
and
B.F. Barger
Charlotte-Mecklenburg Solid Waste Mgmt, Charlotte, NC
http://www.p2pays.org/ref/12/11571.pdf
_____ 5-page PDF

Inexpensive large-capacity bins:

Workshops use a simple bin, a cylinder formed from
a length of 5 cm x 10 cm (2 in x 4 in) welded wire
fencing 90 cm (3 ft) tall and 3.8 m (12 ft 6 in) in length.
This cylinder holds slightly over 1 m3 (roughly 1.4 yd3)
of materials.



Charlotte-Mecklenburg Hands-On Composting Workshops
and Home Composting Method: A Technical Description
D. H. Boekelheide
Home Composting Program, Charlotte, North Carolina
http://www.p2pays.org/ref/12/11572.pdf
_____ 11-page PDF


Bin materials:

The compost bin used in Charlotte's classes is made
of welded wire fencing. Several other public home
composting programs around the US have used wire
bins successfully (Composting Council, 1996). The
relatively low cost of wire bins ($4.50 per unit) keeps
workshops and free bin distributions affordable.

The fencing is medium gage steel wire welded in rectangles
5 cm by 10 cm (2 in x 4 in). The fencing is 90 cm (3 ft)
high (taller fencing (120 cm (4 ft) and higher) is very
inconvenient to work with for people of average height).
Composters make a bin by cutting a 3.75 m (12 ft 6 in)
length of wire and forming it into a cylinder. The ends
of cut wire are bent back to keep the cylinder from
unrolling. Each cylinder bin holds ~1 m3 (~1.4 yd3)
of material.

The ample capacity of the bin is ideal for leaf composting.
Rolls of wire 15 m (50 foot) long retail for $18 each; each
roll makes four bins.


Compost Production:

Each bin, filled according to instructions to capacity
(1 m3), produces about 0.3 m3 of finished compost
(~10.6 ft3). This is enough to amend 3 m2 (32 ft2)
of garden bed (at 7.5 cm (~3 in) coverage), or
topdress an area of 9 m2 (97 ft2) (at 2.5 cm (1 in)
coverage).


Shreddiing:

I do not suggest that composters shred material.
The cost of a shredder might discourage many home
composters, especially low-income families, and
inexpensive shredders can be noisy and inconvenient
to use.

In Charlotte, a home composter can produce nicely
finished compost from leaves in a reasonable time
without shredding. Surprisingly, trials have shown no
clear evidence that shredding Charlotte's autumn leaves
speeds up or improves the composting process. Instead
shredded leaves tend to mat together in hydrophobic
clumps, similar to peat moss, which remain dry and
resist breakdown.

Experienced home composters report excellent results
composting with leaves and grassclippings shredded and
mixed using a lawn mower (Webster, personal
communication; Alameda, 1997).

Although this mix has not worked well in trials without
shredding, using a 'lawnmower as shredder/mixer' as an
inexpensive and convenient way to mix leaves and
grassclippings for home composting merits further testing.


Leaves: The basic compost feedstock:

The most important feedstock for home composting in
Charlotte is autumn leaf drop from hardwoods such as
pin oak (Quercus palustris), willow oak (Q. phellos),
sweet gum (Liquidambar styraciflua), hickories (Carya
spp.) and maples (Acer spp.).

The home compost bin used in Charlotte's system holds
approximately 150 kg (~330 lbs) of leaves per batch
(equivalent to approximately 15 average sized plastic
'lawn waste' bags of leaves, at 10 kg each (~22 lbs).



Nitrogen Supplement - 'Budget' and 'Organic'

Local trials confirm the axiom that leaf piles do not
heat significantly above ambient and compost slowly
without supplemental N. Since the objective of
workshops is to teach a composting method that
works reliably under local conditions (heats readily
to thermophylic temperatures, causes no odor
problems, gives a nicely finished compost in a
reasonable amount of time), participants learn how
to make home compost using an N supplement.

The main feedstock, autumn leaves, has a C:N ratio
of approximately 80:1. A full bin of leaves contains
approximately 40 kg of actual C. The Charlotte method
adds supplemental nitrogen to bring the C:N ratio of
each batch to approximately 3O:l. Approximately
1.3 kg actual N is needed per pile to reach a 30:1
C:N ratio. The leaves contain about 0.5 kg N; thus,
approximately 0.8-1 kg. N is needed to reach
a 30:l ratio.

Charlotte's home composting system uses a purchased
N supplement. Charlotte, an urban area, has few readily
available sources of 'scroungable' N, such as farm
manure. While garden 'greens' (spent bedding plants,
prunings, weeds, and so on) theoretically can provide
N, locally sufficient quantities of 'greens' are not
available for most urban composters (including most
gardeners), particularly at the time of leaf drop in
the fall.

Grass clippings are difficult to home compost
without problems, as discussed above.

Classes offer two choices for adding N: A 'budget'
option and an 'organic gardening' option. Each
workshop selects the type of N they wish to use
in their model pile by majority vote (so far, the
split has been about 50/50).

With either technique, the temperature of the interior
of the composting mass reaches at least 20 C above
ambient, (50 C (122 F), +or- 5 C) within a week.
For a summary of Charlotte's home composting
'recipes' and N sources, please see Tables 2 and 3.



'Organic' Nitrogen Supplement

The 'organic' recipe for compost uses 22.7 kg (50 lbs)
of inexpensive rabbit food (the least expensive local
source of ground or pelleted alfalfa) as an N source,
per batch of compost. Cow manure is not neccessary
in the 'organic' recipe using rabbit food.

The 'organic' method provides about 0.6 kg actual N,
which when added to the 0.5 kg of leaf N gives a total
of about 1.1 kg actual N for the pile. This provides a
C:N ratio of about 42:l for the pile. Curiously, in spite
of the 'higher than optimal' C:N ratio, piles made with
the rabbit pellets consistently heat more rapidly and to
higher temperatures than those made using the budget
method, and as little as 11.3 kg (25 lb, or a half bag)
of rabbit food is sufficient to heat piles made May
through September.

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