April 2011 article: “Hydrologic and Phosphorus Export Behavior of Small Streams in Commercial Poultry-Pasture Watersheds, ” by J. Joshua Romeis, C. Rhett Jackson, L. Mark Risse, Andrew N. Sharpley, and David E. Radcliffe.
Continuous streamflow and mixed-frequency water quality datasets were collected from nine commercial poultry-pasture (AG) and three forested (FORS) headwater streams in the upper Etowah River basin of Georgia to estimate total P (TP) loads and examine variability of hydrologic response and water quality of storm and nonstorm-flow regimes. Phosphorus concentrations and yields from AG watersheds were generally one to two orders of magnitude greater than those from FORS watersheds. Furthermore, intersite differences in P concentrations and yield among the AG sites as a function of site and sample type were also at order-of-magnitude levels.
[Please note: I have quoted and paraphrased freely from the article, but the interpretation is my own!]