Composting can be important for sustainable crop production because it's so rich in minerals -- but, it needs to be made properly.

Last week at the University of Manitoba's annual field day at their research station in Glenlea, Mario Tenuta, the Canada Research Chair in Applied Soil Ecology, demonstrated what good compost looks like.

"The basic keys to composting are to make sure we start off right," he says. "We need some energy in that starting mixture, so in other words we need carbon... We need nitrogen in that system... So the target then we have of a carbon to nitrogen ratio of those nutrients is about 30, we want to target. And we want to target a moisture content -- we don't want to be too moist, because then the microbes will be starved for oxygen, and if it's too dry, then they won't have enough water to move in the compost and also to move nutrients to them in the compost. So we want about 50, 55 percent moisture content."

Tenuta says you can sometimes determine moisture by smell. If the compost smells like it's rotting, it's likely too moist. After that, compost needs wood chips or straw to encourage aeration, and should be in fairly large piles. Then, compost should be turned and it should be warm.

"Insufficient turning is always a big problem, and so we need to be turning, and we need to also be ensuring that we have a high temperature. We want the high temperature to get rid of the pathogens and weed seeds so we can have a safe product... So monitor the temperature. Invest $15 in a soil temperature probe, which you can get at garden stores."