Submitted to: Agricultural Nonpoint Source Pollution: Watershed Management and Hydrology
Publication Type: Abstract Only
Publication Acceptance Date: June 15, 2001
Publication Date: N/A
The trend in livestock production practices in the U.S. is towards fewer facilities but with much greater numbers of animals per facility. The objectives of this study were: 1) assess the amount of phosphorus (P) transported out of a watershed with intensive swine production, 2) model the P transport using the nonpoint source pollution model ArcView-AGNPS, and 3) predict future P export by projecting, swine production trends into the future. A 200-km**2 watershed was selected in central Iowa within two of the top swine producing counties of the U.S. A total of 26 swine production complexes are currently located within the watershed with the majority concentrated in the headwater area. Fourteen sampling locations were established for collection of stream water samples for dissolved reactive (DRP) and total (TP) phosphorus analyses. Samples were collected on a weekly interval at each site beginning in May 2000. The continuous monitoring stations were also established to measure discharge and collect storm event samples. Results of the field monitoring data are compared with simulations from the ArcView-AGNPS model. The average DRP and TP concentrations were 0.11 and 0.22 mg/L, while maximum DRP and TP concentrations were 0.62 and 1.62 mg/L, respectively. There were no significant trends in P concentration between sample sites or sample dates. Under base flow conditions, P export from the watershed was approximately 0.3 kg/day.