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Re: Composting in dairy systems



Ron, Ignacio, and others:  We did a study several years ago (which 
can be accessed on microfiche as an M.Sc. thesis for George Karanja at 
the Univ. of Guelph) which involved comparing composted vs. 
anaerobically stacked manure as a pre-plant source of N for 
orchardgrass.  We collected the manure or compost in 500 lb units 
from a total of about 25 producers if memory serves, with about half 
organic (providers of compost) and half conventional (providers of 
anaerobically stacked manure).  Both beef and dairy operators 
contributed to the study.  

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