See more from this Session: Symposium--Global Importance and Progress of Reducing Anthropogenic Emissions of Nitrous Oxide From Cropping Systems: I
Tuesday, October 18, 2011: 11:15 AM
Henry Gonzalez Convention Center, Room 211, Concourse Level
Emissions of nitrous oxide (N2O), a potent greenhouse gas. are known to multiply serveral several fold with N fertilizer additions to cropland. Rarely do N2O losses represent an agronomic or economic loss to a farmer. Most N2O emission data in the US is or corn or wheat. Little data is available for cotton. We conducted N rate cotton studies under a center pivot in Floydada, TX and with level basin irrigation in Maricopa, AZ. Nitrous oxide emissions were measured weekly between first square and peak bloom. Twenty-four-minute incubation periods with vented chambers were employed, followed by N2O analysis on a ECD-GC. . At both sites, N2O emissions declined as the season progressed, presumably as plant depleted available soil and fertilizer NO3-N. Fluxes were not detectable more than 4 days after irrigation events. Nitrous oxide emissions were low, with a maximum seasonal flux of 367 g N2O-N/ac lost for the 120 lb N/ac fertilizer rate in TX. This is only 0.5% of applied N, and is well below the IPCC default N2O emission factor of 1 %.