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OWMA questioning Ontario's attempt to raise compost moisture levels

Hargreave adds that the new change could actually encourage facilities to work through the Fertilizer Act or NASM, producing an inferior product, and increasing the potential for off-site odours


Wikimedia Commons, Dodo

Wikimedia Commons, Dodo

The Ontario Waste Management Association (OWMA) has been attempting to convince the province to address industry’s outstanding concerns around higher moisture requirements for compost quality standards set to be introduced in July.

“The sector is evolving, and as a result, an open dialogue is important for both sides,” writes Peter Hargreave, OWMA’s director of policy, in an April 9 letter to the Ontario Ministry of the Environment and Climate Change.

The ministry responded to the OWMA’s letter on April 29, noting that there will be no more changes to the proposed guidelines (created in 2012) at this time.

The new guidelines state that moisture levels must remain at 40 per cent for 21 days of the curing period. But Hargreave says many facilities are creating a less wet (or less mature) compost for farming, and there may be no reason to require them to raise moisture levels, something that would require significant cost increases and a much larger carbon footprint.

Higher moisture levels, in part, are an attempt to cut compost odours. But it’s not that simple, says Hargreave.

“If the compost is too mature, it will not as readily supply oxygen and ‘organic food’ for the soil micro organisms,” writes Hargreave. “It underlines the importance of matching the right product with the right application.”

Hargreave adds that the new change could actually encourage facilities to work through the Fertilizer Act or NASM, producing an inferior product, and increasing the potential for off-site odours.

Hargreave also questions the ministry over whether there will be a wider qualifying range during moisture testing, which can have a 5 per cent margin of error.

Read both letters in full on the OWMA website.


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