A dynamic optimization of soil phosphorus status approach could reduce phosphorus fertilizer use by half in China

Sustainable phosphorus (P) management is essential for ensuring crop production while avoiding environmental damage and the depletion of phosphate rock reserves. Despite local demonstration scale successes, the widespread mobilization of smallholder farmers to adopt sustainable management practices remains a challenge, primarily due to the associated high costs and complicated sampling. Here, we propose a dynamic optimization of soil P status (DOP) approach aimed at managing long-term soil P status within the range of agronomic and environmental soil P thresholds, which facilitates the precise determination of optimal P application rates without the need for frequent soil testing. We evaluate the DOP approach in 35,575 on-farm trials, and the results show that it is agronomically acceptable. Our evaluation extends to estimating future soil P status and P fertilizer inputs across all counties in China for three cereal crops (wheat, rice, and maize). The results indicate that, compared to current practices, the DOP approach can achieve a 47.4% reduction in P fertilizer use without any yield penalty. The DOP approach could become an effective tool for global P management to safeguard food security and enhance environmental sustainability. Sustainable phosphorus management is crucial for crop production and environmental protection, yet smallholder farmers face challenges in adopting efficient practices. The study shows that the Dynamic Optimization of Soil Phosphorus approach can reduce fertilizer use by 47.4% without impacting yields.