ABSTRACT
Research and development of improved phosphorus (P) modeling methods is often hampered by the lack of adequate data on P transported in runoff from various soil and land use conditions. These data are needed to enhance model representation of soil P cycling, off-site transport, and linkages to downstream impacts. Such enhancements
are necessary because models are increasingly used to guide legal, regulatory, and programmatic decisions, which directly affect farm income, water-supply protection, and ecological sustainability. Because of these implications, modelers must incorporate state-of-the-art science to accurately represent P mechanisms and to provide corresponding uncertainty estimates, both of which require appropriate P transport data for model calibration and evaluation (Sharpley et al. 2002).
