Recycled nutrients as a phosphorus source for Canadian organic agriculture: a perspective

The challenges associated with the global phosphorus (P) cycle are complex and multifaceted, from geological resource limitation, to P deficiency on arable farmland, to environmental contamination via excess P fertilization. Although no single solution can address all of the challenges associated with the P cycle, the principle of circularity provides a framework toward a more sustainable and food-secure P system. Phosphorus deficiency on farmland is widespread, particularly on organically managed farms due to negative P balances in low-input cropping systems. Recycled nutrient sources divert food and human wastes back onto farmland; they have the potential to ameliorate both the global-scale issues of phosphate rock depletion and environmental contamination and the farm-scale issue of P deficiency, particularly for organic farms. For recycled nutrients to act as viable alternatives to conventional nutrient sources, their ability to supply P and improve yields must be demonstrated. This paper provides an introduction to the importance of recycled fertilizer sources in the global P cycle, and the key role they can play on organic farmland in Canada.