title: Ground cover impacts on nitrogen export from manured riparian pasture.
abstract: Maintaining ground cover of forages may reduce the export of nitrogen (N) from pastures. The objective of this work was to determine the effect of ground cover on N export from pastured riparian areas receiving simulated rainfall. Plots were established on two adjacent sites in the North Carolina Piedmont: one of 10% slope with Appling sandy loam soils and a second of 20% slope with Wedowee sandy loam soils. Both sites had existing mixed tall fescue (Festuca arundinacea Schreb.)-dallisgrass (Paspalum dilatatum Poir.) vegetation. Forage stands were modified to represent a range of ground cover levels: 0, 45, 70, and 95% (bare ground, low, medium, and high cover, respectively), and amended with beef steer (Bos taurus) feces and urine (approximately 200 kg N ha-1). For all rain events combined, mean nitrate N export was greatest from bare ground and was reduced by 34% at low cover, which did not differ from high cover. Mean ammonium N export was slightly elevated (approximately 1.37 kg N ha-1) in months when manures were applied and negligible (<0.02 kg N ha-1) in all other months. For all rain events combined, mean export of total N was greatest from bare ground and was reduced by at least 85% at all other cover levels. Whereas site did not impact N export, results indicated that cover and time of rainfall following manure deposition are important determinants of the impact of riparian grazing.
authors.affiliation: Dep. of Crop Science, North Carolina State Univ., Box 7620, Raleigh, NC 27695, USA. dmbutler@uga.edu
authors.forename: David M
authors.initials: DM
authors.lastname: Butler
authors.forename: Noah N
authors.initials: NN
authors.lastname: Ranells
authors.forename: Dorcas H
authors.initials: DH
authors.lastname: Franklin
authors.forename: Matthew H
authors.initials: MH
authors.lastname: Poore
authors.forename: James T
authors.initials: JT
authors.lastname: Green
mesh_terms: D000818:Animals; D008372:Manure; D009584:Nitrogen / Q000737:chemistry*; D009657:North Carolina; D010944:Plants / Q000737:chemistry*; D011891:Rain; D014556:Urine
chemical_list: D008372:Manure; D009584:Nitrogen