Nitrous oxide emissions and herbage accumulation in smooth bromegrass pastures with nitrogen fertilizer and ruminant urine application

Laura K. Snell, John A. Guretzky, Virginia L. Jin, Rhae A. Drijber, Martha Mamo

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Agricultural soils contribute significantly to nitrous oxide (N2O) emissions, but little data is available on N2O emissions from smooth bromegrass (Bromus inermis Leyss.) pastures. This study evaluated soil N2O emissions and herbage accumulation from smooth bromegrass pasture in eastern Nebraska, USA. Nitrous oxide emissions were measured biweekly from March to October in 2011 and 2012 using vented static chambers on smooth bromegrass plots treated with a factorial combination of five urea nitrogen (N) fertilizer rates (0, 45, 90, 135, and 180 kg ha-1) and two ruminant urine treatments (distilled water and urine). Urine input strongly affected daily and cumulative N2O emissions, but responses to N fertilizer rate depended on growing season rainfall. In 2011, when rainfall was normal, cumulative N2O emissions increased exponentially with N fertilizer rate. In 2012, drought reduced daily and cumulative N2O emission responses to N fertilizer rate. Herbage accumulation ranged from 4.46 Mg ha-1 in unfertilized pasture with distilled water to 16.01 Mg ha-1 in pasture with 180 kg N ha-1 and urine in 2011. In 2012, plots treated with urine had 2.2 times more herbage accumulation than plots treated with distilled water but showed no response to N fertilizer rate. Total applied N lost as N2O ranged from 0-0.6 to 0.5-1.7 % across N fertilizer rates in distilled water and urine treatments, respectively, and thus, support the Intergovernmental Panel on Climate Change default direct emission factors of 1.0 % for N fertilizer additions and 2.0 % for urine excreted by cattle on pasture.

Original languageEnglish (US)
Pages (from-to)223-234
Number of pages12
JournalNutrient Cycling in Agroecosystems
Issue number2
StatePublished - Mar 2014


  • Climate change
  • Greenhouse gases
  • Nitrogen cycling
  • Pasture management
  • Temperate pastures

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Soil Science


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