title: Nitrous oxide emissions from a Northern Great Plains soil as influenced by nitrogen management and cropping systems.
abstract: Field measurements of N2O emissions from soils are limited for cropping systems in the semiarid northern Great Plains (NGP). The objectives were to develop N2O emission-time profiles for cropping systems in the semiarid NGP, define important periods of loss, determine the impact of best management practices on N2O losses, and estimate direct N fertilizer-induced emissions (FIE). No-till (NT) wheat (Triticum Aestivum L.)-fallow, wheat-wheat, and wheat-pea (Pisum sativum), and conventional till (CT) wheat-fallow, all with three N regimes (200 and 100 kg N ha(-1) available N, unfertilized control); plus a perennial grass-alfalfa (Medicago sativa L.) system were sampled over 2 yr using vented chambers. Cumulative 2-yr N2O emissions were modest in contrast to reports from more humid regions. Greatest N2O flux activity occurred following urea-N fertilization (10-wk) and during freeze-thaw cycles. Together these periods comprised up to 84% of the 2-yr total. Nitrification was probably the dominant process responsible for N2O emissions during the post-N fertilization period, while denitrification was more important during freeze-thaw cycles. Cumulative 2-yr N2O-N losses from fertilized regimes were greater for wheat-wheat (1.31 kg N ha(-1)) than wheat-fallow (CT and NT) (0.48 kg N ha(-1)), and wheat-pea (0.71 kg N ha(-1)) due to an additional N fertilization event. Cumulative losses from unfertilized cropping systems were not different from perennial grass-alfalfa (0.28 kg N ha(-1)). Tillage did not affect N2O losses for the wheat-fallow systems. Mean FIE level was equivalent to 0.26% of applied N, and considerably below the Intergovernmental Panel on Climate Change mean default value (1.25%).
authors.affiliation: Dep. of Land Resources and Environmental Sciences, Montana State Univ., Bozeman, MT 59717-3120, USA.
authors.forename: M P
authors.initials: MP
authors.lastname: Dusenbury
authors.forename: R E
authors.initials: RE
authors.lastname: Engel
authors.forename: P R
authors.initials: PR
authors.lastname: Miller
authors.forename: R L
authors.initials: RL
authors.lastname: Lemke
authors.forename: R
authors.initials: R
authors.lastname: Wallander
mesh_terms: D000383:Agriculture / Q000379:methods*; D000393:Air Pollutants / Q000032:analysis*; D004784:Environmental Monitoring; D005308:Fertilizers; D000455:Medicago sativa; D009009:Montana; D009584:Nitrogen; D009609:Nitrous Oxide / Q000032:analysis*; D006109:Poaceae; D012987:Soil
chemical_list: D000393:Air Pollutants; D005308:Fertilizers; D012987:Soil; D009609:Nitrous Oxide; D009584:Nitrogen