209-5 Reducing Nitrous Oxide Emissions and Nitrate Leaching From Grazed Grasslands.

See more from this Division: ASA Section: Environmental Quality
See more from this Session: Nitrous Oxide Emissions From Agricultural Practices: II

Tuesday, November 5, 2013: 11:05 AM
Tampa Convention Center, Room 19

Diana Selbie1, Karl G Richards2, Keith Cameron3, Hong Di3, Jim Moir3 and Gary J Lanigan2, (1)AgResearch, Ruakura, Hamilton, New Zealand
(2)Environment Soils and Landuse, Teagasc, Wexford, Ireland
(3)Department of Soil & Physical Sciences, Lincoln University, Christchurch, New Zealand
Abstract:
In grazed pasture systems, the nitrogen (N) contained in a cattle urine patch may be up to 1200 kg N ha-1.  The majority of this N is in excess of plant requirements and is vulnerable to environmental loss.  In this study, cattle urine was applied at 5 rates of nitrogen, 0, 300, 500, 700 and 1000 kg N ha-1 to soil monolith lysimeters in late autumn in Ireland in two separate years.  Dicyandiamide (DCD) nitrification inhibitor was applied in solution form at 30 kg DCD ha-1 in two split applications following urine.  Measurements of gaseous N emissions, nitrate (NO3-) leaching and pasture N uptake were made for a calendar year following urine application in two consecutive experiments.  Increasing the rate of urine N applied increased the cumulative nitrous oxide (N2O) emissions, NO3- leaching and pasture N uptake in years one and two, and these relationships are described.  The application of DCD reduced the cumulative N2O emissions and NO3- leaching in year one but not in year two.  The pasture N uptake response to the increasing urine N rate was variable.  We suggest the use of nitrification inhibitors and the reduction of urinary N content as two mitigation strategies for N loss from grazed pasture.

See more from this Division: ASA Section: Environmental Quality
See more from this Session: Nitrous Oxide Emissions From Agricultural Practices: II