Struvite application to field corn decreases the risk of environmental phosphorus loss while maintaining crop yield
Vivekananthan Kokulan, Kimberley D. Schneider, Merrin L. Macrae, Henry F. Wilson
Abstract
Phosphorus (P) runoff from agriculture exacerbates eutrophication globally. Despite diverse mitigation options, the issue persists, necessitating the evaluation of slow-release fertilizers for crop production to minimize environmental P losses. Struvite, a P-rich, recycled product with low water solubility, holds promise for minimizing off-site environmental impacts. Nevertheless, the specific implications of adopting struvite remain uncertain, due to the limited information on the potential of struvite-based fertilizers to reduce P losses to the environment without compromising agricultural productivity under field conditions. A two-year field study was conducted in Ontario, Canada, to assess the agronomic potential and environmental implications of struvite application to field corn (Zea mays L.). Phosphorus fertilization strategies evaluated were a control treatment with no P supplements, a struvite treatment, a monoammonium phosphate treatment (MAP), and a blend of struvite and MAP (where struvite provided 25 % of the P, and MAP provided the remaining 75 %). Both struvite (11.4 Mg ha−1) and blend (11.5 Mg ha−1) treatments produced greater grain yields than the control (10.1 Mg ha−1) when averaged across the years. Grain yields from struvite and struvite/MAP blend treatments were statistically similar to that of MAP (10.7 Mg ha−1). However, the MAP treatment exhibited a greater vulnerability to P losses through runoff and leaching processes in both growing and non-growing seasons. Soil test P (Olsen and water-extractable P) concentrations remained consistently elevated for the MAP treatments relative to the control treatment. The results from plant, soil, and water components demonstrated the potential of struvite and struvite/MAP blends to support corn growth, while reducing environmental phosphorus losses. These findings are critical for implementing a circular economy within the agriculture sector and promoting the adoption of struvite as an alternative phosphate fertilizer.