title: Phosphorus losses from grasslands fertilized with broiler litter: EPIC simulations.
abstract: Broiler litter, a mixture of poultry excreta and bedding material, is commonly used to fertilize grasslands in the southeastern USA. Previous work has shown that under certain situations, application of broiler (Gallus gallus domesticus) litter to grasslands may lead to elevated levels of phosphorus (P) in surface runoff. The EPIC simulation model may be a useful tool to identify those situations. This work was conducted to evaluate EPIC's ability to simulate event and annual runoff volume and losses of dissolved reactive phosphorus (DRP) from tall fescue (Festuca arundinacea Schreb.)-bermudagrass [Cynodon dactylon (L.) Pers.] paddocks fertilized with broiler litter. The EPIC simulations of event runoff volume showed a trend toward underestimation, particularly for runoff events >30 mm. On an annual basis, EPIC also tended to underestimate runoff, especially at runoff volumes > 100 mm. Both event and annual runoff estimations were strongly associated with observed values, indicating that model calibration could improve the simulation of surface runoff volume. The relationship between simulated and observed values of DRP loss was relatively poor on an event basis (r=0.65), but was stronger (r=0.75) on an annual basis. In general, EPIC tended to underestimate annual DRP losses. This underestimation was apparently caused by the lack of an explicit mechanism to model broiler litter on the soil surface. These results suggested that additional work on the EPIC P submodel would be warranted to improve its simulation of surface application of broiler litter to grasslands.
authors.affiliation: Dep. of Crop and Soil Environmental Sciences, Virginia Tech, Blacksburg 24061, USA.
authors.forename: S T
authors.initials: ST
authors.lastname: Pierson
authors.forename: M L
authors.initials: ML
authors.lastname: Cabrera
authors.forename: G K
authors.initials: GK
authors.lastname: Evanylo
authors.forename: P D
authors.initials: PD
authors.lastname: Schroeder
authors.forename: D E
authors.initials: DE
authors.lastname: Radcliffe
authors.forename: H A
authors.initials: HA
authors.lastname: Kuykendall
authors.forename: V W
authors.initials: VW
authors.lastname: Benson
authors.forename: J R
authors.initials: JR
authors.lastname: Williams
authors.forename: C S
authors.initials: CS
authors.lastname: Hoveland
authors.forename: M A
authors.initials: MA
authors.lastname: McCann
mesh_terms: D000818:Animals; D004784:Environmental Monitoring; D017745:Incineration; D008372:Manure; D008962:Models, Theoretical; D010758:Phosphorus / Q000032:analysis*; D006109:Poaceae; D011200:Poultry; D011891:Rain; D012037:Refuse Disposal; D012989:Soil Pollutants / Q000032:analysis; D014872:Water Movements; D014873:Water Pollutants / Q000032:analysis
chemical_list: D008372:Manure; D012989:Soil Pollutants; D014873:Water Pollutants; D010758:Phosphorus