Soil phosphorus mapped across China’s drylands to guide future management

Drylands cover about 40% of Earth’s land surface and support more than a third of the global population, yet these regions are highly vulnerable to climate change and human disturbance. Phosphorus is an essential nutrient for plant growth, but unlike carbon and nitrogen, its behavior in dryland soils remains poorly understood, limiting our ability to manage soil fertility and predict ecosystem responses in these sensitive areas.

Researchers compiled soil phosphorus data from more than 1,100 sites across China’s drylands and tested five machine learning models to map where phosphorus is stored and identify what controls its distribution. The best performing model revealed that surface soil phosphorus (0–30 cm) is primarily driven by temperature, while deeper phosphorus (30–100 cm) is more closely linked to microbial activity. In addition, the findings show that grassland soils hold the largest phosphorus stocks compared to other dryland land types, and that stocks are likely to increase under future climate scenarios. This new high-resolution map provides a critical baseline for guiding fertilization, restoring degraded soils, and managing phosphorus sustainably in China’s drylands under global change.