Corn producers have no reason to fear a drop in yield if they replace some of the chemical fertilizers they apply to their fields with fertilizing residual materials (FRMs) such as compost, sewage sludge, and de-inking mill residues.
This is demonstrated by student researcher Jean-Dominic Côté and Professor Lotfi Khiari from the Department of Soils and Agri-Food Engineering at Université Laval in an article published in the journal
Field Crops Research.
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In Quebec, urban activities such as the collection of compostable waste, biomethanization, or wastewater treatment, and industrial activities such as those of paper mills or de-inking plants generate 5.0 million tons (4.55 million tonnes) of organic residues annually. Approximately 65% of these materials are recycled, notably into compost (23% of the recycled tonnage) or into FRMs applied to agricultural fields (34% of the recycled tonnage). About one-third of organic residues still end up in landfills or incinerators.
"From a theoretical standpoint, using FRMs offers undeniable advantages for ensuring sustainable agriculture. When we send our waste to landfills or incineration, the nutrients they contain are, in a way, lost. By recycling our organic waste, we ensure that we close the loop by reintroducing nutrients into the production cycle. FRMs also contribute to maintaining and improving the physical and chemical properties of soils as well as their biological activity," emphasizes Jean-Dominic Côté.
The idea of replacing chemical fertilizers with FRMs is not universally accepted among corn producers. Indeed, some fear that FRMs may lead to lower field yields due to the lower bioavailability of the nutrients they contain. To determine whether these concerns were justified, Jean-Dominic Côté and Lotfi Khiari conducted experiments at the agronomy station of Université Laval, located in St-Augustin-de-Desmaures, and at the experimental farm of the Research and Development Institute for the Agri-Environment (IRDA), located in Saint-Lambert-de-Lauzon.
"We tested, over two growing seasons, the effect of eight types of FRMs on the nutritional balance and yields of corn. The amount of FRM used was sufficient to fully meet the plants' phosphorus needs and one-third of their nitrogen needs. The remainder was supplemented with chemical fertilizers," specifies the student researcher.
The data obtained show that all FRMs tested in combination with chemical fertilizers ensure a nutritional balance at least as good as fertilization based solely on chemical fertilizers. As for yields, the FRM-chemical fertilizer combinations perform as well as chemical fertilizers alone.
"Our results suggest that FRMs can replace a portion of chemical fertilizers without compromising plant health or yield," summarizes Jean-Dominic Côté. "Transforming organic waste into agronomic inputs contributes to sustainable agriculture and the resilience of agricultural systems while reducing production costs."
In recent years, concerns that FRMs may contain certain contaminants, notably fluorinated organic compounds also known as forever chemicals, may have dampened agricultural interest in these types of soil amendments, notes the student researcher.
"The environmental aspect of recycling FRMs must absolutely be studied to guarantee their safety and reassure the public," he insists. "That is why our collaborators at Université de Montréal, McGill University, the Québec Centre for Environmental Analysis Expertise, and IRDA are investigating the issue."