Page 24 - Green knowledge 2024

Photo: Erling Fløistad
Sustainable management of flower waste
Every year, thousands of tonnes of plant material from florists across the country are
discarded. In collaboration with two industry partners, NIBIO is exploring methods for a
more sustainable approach to managing plant waste.
In partnership with Mester Grønn and Axel Wiig,
NIBIO has investigated how flowers and decorative
greenery waste can be composted sustainably. The
project included comprehensive analyses of pesticide
residues in samples from mixed plant waste, differ-
ent flower species, and green plants.
A total of around 130 pesticides were detected in the
waste, most of which are EU-approved. However,
some unauthorised substances were also found.
Researchers aim to increase knowledge about the
properties of different pesticides and determine the
best ways to treat plant waste so that harmful sub-
stances break down, making the compost safe to use.
The trials, which involved both small- and large-
scale composting processes in oxygen-rich environ-
ments, showed that most pesticides decrease in
number and concentration during regular compost-
ing. However, researchers discovered that some sub-
stances, particularly those containing fluorine or
chlorine, as well as a few others, break down very
slowly and remain in the compost for a longer time.
Therefore, optimising the composting process to
ensure the best possible conditions for degradation is
essential.
Most of the substances detected, with a few excep-
tions, have soil half-lives ranging from 120 to 500
days, according to the pesticide properties database.
For some pesticides, an anaerobic (oxygen-free)
phase may help accelerate the breakdown of persis-
tent compounds.
Purpose: To gather knowledge and provide recommendations for sustainable methods of handling plant
waste with high pesticide concentrations.
Collaboration: Mester Grønn, Axel Wiig, and Bernt Snapa
Funding: Norwegian Agriculture Agency
Contact: Senior Research Scientist Trine Eggen, Division of Environment and Natural Resources.
Email: trine.eggen@nibio.no | Phone: +47 909 97 074
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