Overuse of P fertilizer is common in intensive wheat-maize cropping systems in the Quzhou county and North China Plain. Most of P fertilizer was remained in soil and seriously increased soil P surplus, as a result, very low P use efficiency and environmental risk are caused. Therefore, we will develop a site based P fertilizer advice, matching soil P supply to the plant P demand at field level and then assess and map the spatial variation in sustainable P inputs versus current P inputs in the Quzhou county; if possible, we would like to upscale the result to the North China Plain.