Potato Response to Struvite Compared with Conventional Phosphorus Fertilizer in Eastern Canada

In acidic soils with high phosphorus (P) fixing capacity, P application at levels higher than crop requirements is common in crops with high P demands such as potato (Solanum tuberosum L.), which could lead to eutrophication. Recycled sources of P fertilizer, such as struvite, can be efficient in meeting crop P demands while minimizing P losses. The objective of this study-conducted in four provinces over 3 yr (2016-2018, with 12 sites in total) in Eastern Canada-was to assess potato response to P fertilizer as triple superphosphate (TSP) or a mixture of TSP with struvite. Eight P treatments were applied with five increasing P rates as TSP (0, 26, 52, 79, and 105 kg P ha(-1)) and three treatments as a mixture of TSP and struvite (25, 50, and 75% (w/w) struvite) at a rate of 79 kg P ha(-1). Phosphorus availability indices measured multiple times over the growing season were composed of Mehlich-3 extracted P (P-M3), soil P adsorbed on anion exchange membranes (P-AEMs), and petiole P-PO4 (P-petiole) concentrations. There was a potato yield response to P inputs at all sites, with the control treatment showing lower potato yield at all sites. Potato yield, P-petiole, P-M3, and P-AEMs were comparable between 100% TSP and TSP+struvite at the same rate, except at one site where struvite at a higher proportion depressed yield and was associated with lower P uptake. Overall, the use of struvite could be a sustainable mean to address long-term globally P scarcity.