Wastewater-derived struvite is a promising phosphorus (P) fertilizer but more information on its behaviour in soil is needed to guide management practices for this slow-release fertilizer. After 20 days of incubation in two contrasting low-P soils in Petri dishes at two temperatures, the Olsen-P concentrations in soil surrounding struvite granules were 30–122 mg kg⁻¹, which were much lower than after amendment with monoammonium phosphate (MAP) (435–1063 mg kg⁻¹). Olsen-P concentrations further from the granule showed that MAP fertilized a larger volume of soil than struvite. Thus, the fertilizing effect of struvite may be very localized in soil.