As part of the study, we had the producers fill in a detailed
questionnaire to obtain information on anything we could think of
that might affect rate of breakdown and release of N (e.g. rate of
bedding, type of bedding, ration composition, type of stock, use of
pharmaceuticals/probiotics/homeopathic remedies etc.).
Without going into detail about the results (another time), I'd like
to comment on one surprising aspect of composting practice. NONE of
the organic producers "turned" their compost or owned specialized
equipment of any kind. The entire process of composting of solid
manure was accomplished with existing machinery (one exception was a
chappie who had built a special, open-sided, cement-floored shed for
pre- composting). The practice was strikingly similar across all the
organic farms studied, namely,
a) heavy rate of bedding - several times that of conventional
producers
b) always LONG cereal straw used for bedding - not chopped straw or
sawdust or chips
c) material to be composted was either pre-composted (one case only,
to allow excess moisture to drain out and be collected in a liquid
manure system prior to going out to the field) OR taken straight out
to a convenient site - which varied from year to year - to be laid
down in a windrow.
d) windrow dimensions were critical, and were quite consistent among
farmers; as I recall it, the initial windrow was about 8-10' high and
perhaps 15' wide, and as long as needed to manage all the manure.
During composting, which required several months or more, the windrow
pancaked down upon itself, such that what we sampled as mature
compost was perhaps 4-6' high.
e) the combination of high rates of long straw and relatively narrow
windrows served to maximize passive airflow into the windrow. The
straw was believed to act as channels, while the width and height was
kept small, to maximize surface area:volume, to allow air to
penetrate throughout the volume of the windrow
f) none of them turned the windrow. The only equipment used was
either a simple spreader, or, if the material was a bit dry, a dump
loader to avoid over-aerating the raw material and promoting excessive
heating.
In sum, there is NO NEED to purchase special equipment to produce
excellent quality, farm-scale, organic compost from solid manure.
The trend in our area - humid temperate - is towards pre-composting,
which requires a shed of some kind to drain off and collect effluent
before taking the manure out to the windrow. I know of one
conventional beef producer who also built a dual-purpose shed, to
serve as hay storage in early fall, gradually being displaced by
manure as the hay was fed out. He is seriously interested in
nutrient cycling and doesn't want to lose anything to leaching. His
manure is anaerobically stacked - not composted - but it is out of
the weather.
Of course, as noted by Ron, composting per se is only an issue if you
have a significant interval of confinement or drylotting each year.
Otherwise, grazing cattle will do the work for you. Ann
ACLARK@crop.uoguelph.ca
Dr. E. Ann Clark
Associate Professor
Crop Science
University of Guelph
Guelph, ON N1G 2W1
Phone: 519-824-4120 Ext. 2508
FAX: 519 763-8933