title: Biotic and abiotic controls on nitrogen leaching losses into waterways during successive bovine urine application to soil.
abstract: Cattle waste products high in nitrogen (N) that enter waterways via rainfall runoff can contribute to aquatic ecosystem health deterioration. It is well established that N leaching from this source can be reduced by plant assimilation, e.g. pasture grass. Additionally, N leaching can be reduced when there is sufficient carbon (C) in the soil such as plant litterfall to stimulate microbial processes, i.e. denitrification, which off-gas N from the soil profile. However, the relative importance of these two processes is not well understood. A soil microcosm experiment was conducted to determine the role of biotic processes, pasture grass and microbial activity, and abiotic processes such as soil sorption, in reducing N leaching loss, during successive additions of bovine urine. Pasture grass was the most effective soil cover in reducing N leaching losses, which leached 70% less N compared to exposed soil. Successive application of urine to the soil resulted in N accumulation, after which there was a breaking point indicated by high N leaching losses. This is likely to be due to the low C:N ratio within the soil profiles treated with urine (molar ratio 8:1) compared to water treated soils (30:1). In this experiment we examined the role of C addition in reducing N losses and showed that the addition of glucose can temporarily reduce N leaching. Overall, our results demonstrated that plant uptake of N was a more important process in preventing N leaching than microbial processes.
authors.affiliation: Australian Rivers Institute, and School of Environment, Griffith University, Kessels Rd, Nathan, Queensland, 4111, Australia. Electronic address: amanda.neilen@griffithuni.edu.au.
authors.forename: Amanda D
authors.initials: AD
authors.lastname: Neilen
authors.affiliation: Environmental Futures Research Institute, and School of Environment, Griffith University, Kessels Rd, Nathan, Brisbane, QLD 4111, Australia.
authors.forename: Chengrong R
authors.initials: CR
authors.lastname: Chen
authors.affiliation: Australian Rivers Institute, and School of Environment, Griffith University, Kessels Rd, Nathan, Queensland, 4111, Australia.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Faggotter
authors.affiliation: Australian Rivers Institute, and School of Environment, Griffith University, Kessels Rd, Nathan, Queensland, 4111, Australia.
authors.forename: Tanya L
authors.initials: TL
authors.lastname: Ellison
authors.affiliation: Australian Rivers Institute, and School of Environment, Griffith University, Kessels Rd, Nathan, Queensland, 4111, Australia.
authors.forename: Michele A
authors.initials: MA
authors.lastname: Burford
mesh_terms: D000818:Animals; D001315:Australia; D002244:Carbon / Q000032:analysis; D002417:Cattle; D055598:Chemical Phenomena; D017753:Ecosystem; D004784:Environmental Monitoring; D006863:Hydrogen-Ion Concentration; D009584:Nitrogen / Q000032:analysis*; D006109:Poaceae / Q000737:chemistry; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis; D014556:Urine / Q000737:chemistry*; D014867:Water / Q000737:chemistry*; D014872:Water Movements; D014873:Water Pollutants / Q000032:analysis*
chemical_list: D012987:Soil; D012989:Soil Pollutants; D014873:Water Pollutants; D014867:Water; D002244:Carbon; D009584:Nitrogen
keywords: Biochar; Livestock; Stoichiometry; Urine patch; Watershed