Submitted to: International Symposium on Agricultural & Food Processing Wastes Proceeding
Publication Type: Abstract Only
Publication Acceptance Date: 10/14/2003
Publication Date: 10/14/2003
Citation: Sauer, T.J., Sreematkandalam, K.C., Tim, U.S., James, D.E., Hatfield, J.L. Measurement and Prediction of Phosphorus Transport From Swine Manure at the Watershed Scale [abstract]. International Symposium on Agricultural & Food Processing Wastes Proceeding. American Society of Agricultural Engineers. p. 535.
Technical Abstract: Livestock production facilities are coming under increased scrutiny with regard to runoff of phosphorus (P) from fields receiving animal manures. The objective of this study was to measure and simulate how swine manure management affects P export from a watershed with intensive swine production. Stream water sampling (1-3 week intervals) was conducted for one year at 14 locations within the Tipton Creek watershed in central Iowa. Data on soil and manure P concentrations and amounts were also collected. Geographic Information System (GIS) data layers (topography, soils, land use, and land cover) were prepared to create the input data necessary to run the Agricultural Non-Point Source model (AGNPS). Total P export from the Tipton Creek watershed from April 1, 2000 to April 1, 2001 was estimated at 10.6 metric tons for an average of 0.52 kg of P lost per ha. Four rainfall events during the 2000 growing season and snowmelt in March 2001 were responsible for the transport of 91% of the P from the watershed. Using animal inventory numbers and standard P excretion values, swine manure was estimated to supply approximately 35% of the land-applied P. AGNPS simulations were completed with an assumed 5% annual increase in swine production and subsequent increase in P application to the soils of the watershed. These simulations indicated that such a production trend, without any changes in current management, could result in a 40% increase in P transport from the watershed after 5 years. However, a combination of swine diets with lower P and use of high available-P feedstuffs and/or phytase enzyme can reduce P excretion by as much as 50%. Adoption of these practices over the next 5 years could prevent any increase in P production from the swine facilities in the watershed. Key Words: swine manure, phosphorus, water quality, AGNPS model