Evaluating spatial interaction of soil property with non‐point source pollution at watershed scale: The phosphorus indicator in Northeast China

► Spatial dynamics of NPS phosphorus pollution with soil property at watershed scale are analyzed. ► Impacts of agricultural practice on soil property at spatial and vertical are identified. ► Eight soil parameters at two depths observe different patterns with NPS phosphorus loading. ► Watershed soil copper and cadmium in subsurface are useful indicators.