Co-Composting Material

Co-composting material is referred to any material added to the composting pile to aid in the composting process. Mortalities are high in nitrogen; therefore, co-composting materials high in carbon such as sawdust, straw, and woodchips should be used when composting deadstock. Particle size should also be taken into consideration. The co-compost material should be large enough to allow air flow into the pile, but small enough not to cool the pile. Particle size ranging from 0.25 - 2 inches should be targeted.

The amount of carcass:co-compost material required on a volume basis shown below has proven to be effective for mortality composting. For all other carcass:co-compost ratios, please contact your local GO Office.

Co-compost	Carcass:Co-compost ratio
Sawdust	1:12
Straw	1:3-5
Woodchips	1:4-6

Note: If manure is used as a co-compost material a Manure Management Plan (MMP) must be filed with Manitoba Conservation for operations with 300 or more animal units.

Type	Advantages	Disadvantages
Sawdust	Fine particle size Retains head Sheds rain water Absorbent High carbon content Allows for air infiltration	Availability may be limited
Straw	Less straw required than sawdust Readily available	Core temperature may not be as high as with sawdust Requires water control management More susceptible to leaching then sawdust May form air pockets
Woodchips	Provides excellent surface contact Easy to work with Helps mask odours	Availability may be limited

Other materials can be used as bulking agents (see table below) such as old silage, manure/litter, finished compost (not exceeding 50%) and bedding.

Origin	C:N Ratio, nutrients	Structure, porosity	Moisture - as is	Degradability	Treatment required	Cautions
Agricultural Residuals
Poultry manure (fresh, no litter)	10	Poor	Moist	Good	Bulking material	Odour
Poultry manure (with litter)	13-30	Medium	Low-dry	Medium	-	Odour
Slurry (urine) liquid	2-3	Poor	Liquid	Good	Mix with dry matter	Odour
Manure (cattle) liquid	8-13	Poor	Liquid	Good	Mix with dry matter	Odour
Manure (pig)	5-7	Poor	High	Good	-	Odour, moisture
Cattle manure	20	Medium	Medium	High	-	-
Manure with straw	25-30	Good	Good	Medium	-	-
Horse manure	25	Good	Good	Medium	-	-
Vegetable wastes	13	Poor	Moist	High	-	Low pH, Odour
Straw:
- Oat/Rye	60	Good	Dry	Medium	Rough chopping	-
- Wheat	100	Good	Dry	Medium	Rough chopping	-
- Barley/Pulses	40-50	Good	Dry	High	-	-
Wood and Lumber Industry Materials
Bark	100-300; Low P, Ca; Low pH	Very Good	Medium; Good	Very Good	Pre-grind	-
Paper sludge	100-110	Medium to Poor	Very Moist	Medium	Presscake	Dioxins
Cotton sludge	20-40; N-rich; Low P, K	Poor	Very Moist	Very Good	Pressed	-
Sawdust
Beech	~100	Very Good	≤ 50% good	Excellent	Already ground	-
Fir	~230	Very Good	≤ 50% good	Medium	Already ground	-
Aged	<100	Very Good	≤ 50% good	Poor	Already ground	-
Garden / Landscape Materials
Wood chips	40-100	Good	Too Dry	Low	Grinding	Coarseness
Garden wastes	20-60	Good	Medium	Medium	Grinding	-
Green foliage	30-60	Medium to Good	Good/Dry	Good	-	-
Leaves	-	Good	-	-	-	Matting
Grass clippings	12-25	Poor	Moist	High	Bulking material, pre-drying	Odour

Agriculture

Co-Composting Material