August 23, 2013, Prince George, BC - New research from the University of Northern British Columbia suggests
that waste from municipalities and bioenergy plants can be combined to
make an ideal fertilizer and reduce material added to
The study provides the first insights into the use of wood
ash and biosolids as soil amendments for nurseries, forests, and mines
in a northern boreal climate.
“What we found is that by combining these two waste materials, we
make them more than the sum of their parts,” say UNBC Environmental
Science Professor Mike Rutherford and Forestry Professor Hugues
Massicotte, who both supervised the project conducted by UNBC student
Nichola Gilbert. “Bioenergy ash is rich in nutrients, but low in
nitrogen while biosolids are high in organic matter and nitrogen.
They’re a perfect match that can increase plant growth by more than 200
percent in some soils.”
The research aimed to identify the amounts of ash and biosolids
that would best enhance soils in Northern BC. Trials were undertaken to
document the growth of plants in deficient soils that had been enriched
only with ash, with biosolids, and with ash/biosolid combinations. The
project used ash from the University’s award-winning bioenergy plant,
local industries, and locally-sourced biosolids. Biosolids are defined
as stabilized sewage resulting from municipal wastewater treatment
plants, and are sometimes used as fertilizers.
For four months, willow and poplar cuttings were grown in two
soils: one from a copper-molybdenum mine site (Gibraltar Mine north of
Williams Lake), and one from a bioenergy plantation (Pacific
Regeneration Technologies) near Prince George. Overall, wood ash
combined with biosolids proved the most fertile.
Locally, both Canfor Pulp and UNBC’s bioenergy plant are producing
ash, although many rural and First Nations, off-grid communities in
Northern BC have expressed interest in implementing this technology in
their communities. Some, such as Gitsegukla near Hazelton, have already
started. There are also several local companies producing bioenergy
crops, such as Red Rock Bioenergy Crops south of Prince George.
“With industry and communities already operating bioenergy plants –
or planning to implement them – this research illustrates potential
uses for the ash that emerges from these plants,” says Dr. Rutherford.
“The potential is there for communities to complete the ‘sustainability
loop,’ and make use of the ash that comes from the bioenergy plants that
provide their energy, and the waste produced by their community, to
produce the next crop of biomass for the bioenergy plant, and reclaim
land after forestry and mining.”
According to the researchers, additional study is needed to
optimise the use of ash/biosolid fertilizer on agricultural lands,
nurseries, and forested lands. There are opportunities for the use of
these amendments in various reclamation and remediation strategies, as
“Interestingly, the growth response was more obvious with willow
trees compared to poplar,” says Dr. Rutherford. “This reveals that
different plant species will behave differently to various amendment
levels. The responses will also be determined by soil type.”
Financial support for this research was provided by the Natural
Sciences and Engineering Research Council, Canfor Pulp Limited
Partnership, Pacific Regeneration Technologies, Gibraltar (Taseko) Mine,
and the UNBC I.K. Barber Enhanced Forestry Laboratory.