Like any recipe, making a good composted manure requires the right ingredients, a proper mixer and some heat.
“There are a lot of misconceptions as to what composting actually is, some think that if you have a pile of manure it’s called composting, it really isn’t,” said Mario Tenuta. “So we want to talk to growers about what would be some recipes for composting.”
The University of Manitoba soil ecologist is one of several researchers operating out of the Glenlea Research Station just south of Winnipeg, where a pilot composting project aims to introduce producers to the practice.
Piled in pyramid-shaped windrows about six or seven feet wide and just as tall, visitors to the site can see what composting looks — and smells like — at various stages.
“If you’re doing it properly, you shouldn’t have a smell,” said Tenuta, adding the final product is stable, dense, nutrient rich and easy to transport.
But it takes the right combination to get the desired results.
“We don’t want too much water, we don’t want too little, we don’t want too much nitrogen and we don’t want too little nitrogen, there is a right sweet spot,” said the researcher. “And once you mix all that stuff together the microbes take over.”
Those mighty microbes — bacteria and fungi — also provide the heat.
“In soil the heat generated by microbes is inconsequential, because soil is a good conductor of heat, and it wicks the heat away from the microbes, but a pile of organic material is a good insulator,” said Tenuta. “So the heat that those microbes are generating in the pile stays in the pile and the pile starts to get warm.”
And don’t think winter will stop those organisms from heating things up.
“So our work has shown that we have no problem composting in the winter, even if it’s -30 outside we can compost… because the microbes are generating enough heat, and that manure is a wonderful heat insulator,” he said, noting heat is crucial to removing animal pathogens and rendering weed seeds inert.
St. Norbert-based market gardener Bruce Berry of Almost Urban Vegetables knows the problems that can accompany improperly composted manure first hand.
“It’s much better for us to have compost in our hands than some manure that was turned a couple of times,” he said. “What we’re finding is that with some of the materials we are bringing in, they’re loaded with weed seeds, so I’m really just importing next year’s hours in the garden weeding.”
But for now, Berry doesn’t have to worry about the quality of his compost. He’s importing it from the pilot project at Glenlea.
“For me it’s a great enabler to have decent-quality stuff to work with, it’s just going to up our game,” he said, adding intensive vegetable production requires nutrient-rich soil.
The compost made at Glenlea is also used on the site’s 24-year-long organics study.
“The compost additions every several years is enough to keep that system going, so nitrogen is fixed biologically, through legumes, be it alfalfa, soybeans, and… compost addition provides the phosphorus,” said Tenuta.
Turning compost is also crucial, he added, noting aeration is part of the composting process. At Glenlea, mixing and turning is done with the help of some specialized machines.
“Think of a bale buster, or a Kitchen-Aid mixer,” he said. “Basically a big huge thing like that and you throw a bale under it, and it had these grinders… then we can start adding the solids, we can start adding the water, and mix it up. Then we open up a side chute, and out it comes.”
However, windrows can also be made using something like a front-end loader. Compost is turned with something similar to a snow blower, but much less dramatic.
And while the Glenlea study is currently focused on manure composting, Tenuta would like to expand the scope of composting projects in the future.
“We’d like to see this demo project grow, for example… how much food do people eat, say at the University of Manitoba? Think of all that organic material and also all those paper towels,” he said. “That’s all compostable material… and we’d like to be diverting that to Glenlea, mixing in this animal manure and composting that material — so it could then go back to providing nutrients and a healthy product for the soil.”