Orthophosphate versus polyphosphate fertilizers in plant nutrition: a review of crop responses

Phosphorus (P) is an essential macronutrient required for plant growth and productivity, yet its use efficiency in agricultural systems remains low due to strong soil fixation and limited mobility. Orthophosphate fertilizers are the most widely used phosphorus sources; however, polyphosphate fertilizers have been proposed as an alternative due to their potential to reduce phosphorus fixation and enhance plant uptake. Despite decades of research, there is no clear consensus on whether orthophosphate or polyphosphate fertilizers are superior for crop production, as contrasting results have been reported across studies. This review synthesizes published studies that directly compared orthophosphate and polyphosphate fertilizers across a range of crops, soil types, and environmental conditions. More than half of the reviewed studies reported no significant differences in crop yield or phosphorus uptake between the two fertilizer forms, suggesting comparable agronomic performance. Most studies focused on cereals and tuber crops, with limited information available for perennial and other phosphorus-inefficient crops. In addition, many studies reported biomass rather than harvested yield. Overall, the relative effectiveness of orthophosphate and polyphosphate fertilizers appears to be site-specific and influenced by soil properties, crop type, and management practices. Further field-based research that includes yield measurements across a wider range of crops is required to improve phosphorus use efficiency and support environmentally sustainable fertilization strategies.