A review and meta‐analysis of the agricultural potential of struvite as a phosphorus fertilizer

Abstract The low water solubility of struvite is thought to limit its agronomic utility as a phosphorus (P) fertilizer compared with highly soluble P fertilizers. Furthermore, struvite's fertilizer potential is complicated by its hypothesized soil pH‐dependent solubility, crop‐specific interactions, and limited availability of struvite‐derived N, which may explain conflicting reports of crop responses to struvite compared with conventional P fertilizers. A systematic literature review and meta‐analysis was conducted to evaluate the effects of soil pH, soil test P (STP), P rate, struvite particle size, and struvite‐derived N on crop aboveground biomass, P concentration, P uptake, and N uptake. Struvite‐fertilized plants yielded higher biomass, P concentration, and P uptake compared with ammonium phosphates, and superphosphates in soils with pH < 6 and crop responses decreased with increasing pH. Crop responses to struvite were inversely related to experiment duration to soil mass ratios (d kg −1 ) used in greenhouse studies, opposite to the hypothesized benefit of more roots per unit soil on struvite dissolution. The proportion of total N applied derived from struvite increased with increasing struvite‐P application rate and was inversely related to total N uptake, likely due to the increased crop reliance on slowly available struvite‐N. Crop responses were potentially overestimated by high STP and/or P rates and underestimated due to N limitation from large proportions of total N applied derived from struvite. Evaluations of struvite collectively indicate its efficacy as a P fertilizer is affected by soil pH and its contribution to total N application.