ARS | Publication request: Nitrous oxide emissions from smooth bromegrass pasture under nitrogen fertilizer and bovine urine application in eastern Nebraska

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 6, 2011
Publication Date: N/A

Technical Abstract: Nitrous oxide (N2O) is a greenhouse gas primarily produced in soils by denitrifying and nitrifying organisms. In terms of global warming potential (GWP), N2O has 310 times the GWP of carbon dioxide (CO2). Atmospheric N2O concentrations have increased by 18% since the industrial revolution with agricultural soils responsible for 70% of emissions in the United States. Tracking N2O emissions in the United States prepares the country for future legislation and carbon budgeting. Although the measurement of N2O has become more focused in the last 20 years, little data has been collected in managed pasture ecosystems. This study focused on the production of N2O in smooth brome (Bromus inermis Leyss.) pastures in eastern Nebraska. Thirty smooth brome plots (5m x 5m) were treated with five different fertilizer treatments (0, 45, 90, 135, and 180 kg/ha) and two urine treatments (urine and no urine). N2O emissions were recorded biweekly from March to October using the Hutchinson and Mosier (1981) vented chamber method. Preliminary findings revealed a significant interaction between Nitrogen fertilizer rate (p<0.005), urine application (p <0.001), and sampling date (p<0.0001). Both N and urine treatments resulted in higher N2O emissions compared to control plots. This study found ideal conditions for denitrifying and nitrifying activity occurred in soil at 15.5oC with 55% soil moisture which resulted in N2O emissions up to 297.22 ng N/cm2/h. The research discovered higher N2O emissions than cited in previous studies and significant daily losses raise questions about timing of sampling and further research.