Economic Assessment of Potato Response to Struvite and Conventional Phosphorus Fertilizer in Eastern Canada

Phosphorus (P) fertilizers are essential but potentially inefficient, especially in shallowrooted potatoes. A 3-year field experiment (2016-2018) was conducted in four distinct sites in Eastern Canada to investigate economic and environmental impacts of struvite-based slow-release and conventional P fertilizers in potato ( Solanum tuberosum L.). Marginal return (MR = gross revenue-total operating cost) was assessed for different P treatments (0, 60, 120, 180, and 240 kg P 2 O 5 ha -1 ) from triple super phosphate (TSP) and for different mixtures of struvite (25%, 50%, and 75%) and TSP at 180 P 2 O 5 kg ha -1 . Comparable MRs to TSP at a rate of 180 kg P2O5 ha- 1 were obtained with a mixture of 75% TSP and 25% struvite across sites and years. Results demonstrated that a struvite-based mixture can be a viable alternative to conventional P fertilizers, improving profitability and lowering potential cumulative environmental costs associated with P application by $8-$24 ha -1 year -1 for potato production.