title: Effect of broadcast manure on runoff phosphorus concentrations over successive rainfall events.
abstract: Concern over eutrophication has directed attention to manure management effects on phosphorus (P) loss in runoff. This study evaluates the effects of manure application rate and type on runoff P concentrations from two, acidic agricultural soils over successive runoff events. Soils were packed into 100- x 20- x 5-cm runoff boxes and broadcast with three manures (dairy, Bos taurus, layer poultry, Gallus gallus; swine, Sus scrofa) at six rates, from 0 to 150 kg total phosphorus (TP) ha(-1). Simulated rainfall (70 mm h(-1)) was applied until 30 min of runoff was collected 3, 10, and 24 d after manure application. Application rate was related to runoff P (r2 = 0.50-0.98), due to increased concentrations of dissolved reactive phosphorus (DRP) in runoff; as application rate increased, so did the contribution of DRP to runoff TP. Varied concentrations of water-extractable phosphorus (WEP) in manures (2-8 g WEP kg(-1)) resulted in significantly lower DRP concentrations in runoff from dairy manure treatments (0.4-2.2 mg DRP L(-1)) than from poultry (0.3-32.5 mg DRP L(-1)) and swine manure treatments (0.3-22.7 mg DRP L(-1)). Differences in runoff DRP concentrations related to manure type and application rate were diminished by repeated rainfall events, probably as a result of manure P translocation into the soil and removal of applied P by runoff. Differential erosion of broadcast manure caused significant differences in runoff TP concentrations between soils. Results highlight the important, but transient, role of soluble P in manure on runoff P, and point to the interactive effects of management and soils on runoff P losses.
authors.affiliation: USDA-ARS, Pasture Systems and Watershed Management Research Unit, University Park, PA 16802-3702, USA. pjk9@psu.edu
authors.forename: Peter J A
authors.initials: PJ
authors.lastname: Kleinman
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Sharpley
mesh_terms: D000383:Agriculture; D000818:Animals; D002417:Cattle; D004784:Environmental Monitoring; D005068:Eutrophication; D008372:Manure; D010758:Phosphorus / Q000032:analysis* / Q000737:chemistry; D011200:Poultry; D011891:Rain; D012995:Solubility; D013552:Swine; D014872:Water Movements
chemical_list: D008372:Manure; D010758:Phosphorus