Pulp mill waste could find new use as fertilizer

Pulp mill waste heading for a landfill could have a second life as an organic fertilizer.

A University of Alberta research project suggested waste could help reduce the environmental impact of using conventional fertilizers while improving soil and tree growth.

A two-year study of a hybrid poplar tree plantation in northern Alberta showed that compared with using conventional fertilizers alone, adding wood and other fibers left over from pulp and paper production, reduced harmful greenhouse gas emissions from the soil.

Combining these biosolids and conventional fertilizer also improved soil fertility.

Scott Chang is the study’s lead author and a professor in the Faculty of Agricultural, Life and Environmental Sciences. He said the findings provide new insight into what effect biosolids could have if redirected for use on tree plantations that feed the forest industry.

Conventional fertilizer, containing industrially produced urea, has been shown to stimulate greenhouse gas emissions from soil. Though pulp mill biosolids are generally rich in organic content and low in toxicity, it wasn’t known how they might also have an effect.

Chang said the results of the study show the potential for developing a strategy to manage pulp mill waste.

“Repurposing biosolids as an organic fertilizer, which may help reduce greenhouse gas emissions, could improve the sustainability of the pulp and paper industry,” Chang said.